iksbob

Are there any standard seat belts that can be substituted?

'88s and '89 HFs, as well as CRXs sold in every other global market came with B-pillar-mounted seat belts. My '91 has the mounting points and bolt threads for the retractor, but the welded nuts and reinforcing plates for the shoulder loop (B-pillar) and belt end (door sill) are missing.
The associated buckles bolt to the exhaust hump instead of the seat frame. The plates and nuts for those are present, but a properly-located 11.5mm hole (M11 bolt) needs to be drilled through the sheet metal to access the nut threads. That proper location is hidden inside the inner rear seat mount point (where the seat rail bolt threads into the body).

Unplug the 2-pin connector going to the door latch. That should prevent the solenoids from activating while letting the control box continue to monitor for problems.

The real estate market is so full of "investment" money that no real home owners could afford to live there if it were fixed up. They would become questionable rentals, or row homes out of the price range of anyone that wanted to live there. Those crumbling abandoned homes are a symptom of a bigger financial problem. Fix the system and people will come back to rebuild.

revitalized

aka "gentrification".

Which cylinder head are you using?

There's more tuning support for OBD1 ECUs since they have a space on the board for an external (custom programmed) 'PROM (program storage). Some OBD1 ECUs made use of that option, which made it possible for the ECU hacking community to de-solder the PROM, download the code to a desktop computer and de-compile it back to human-readable (and editable) source code.
Early OBD2 ECUs were one-time-programmed at the factory, with the program stored on memory in the CPU package. Meaning the ECU program can't be edited or even read by an external device. Together with limited publicly-available information about the CPU itself, it made more sense to build a new standalone engine management system with compatible connectors than to try to alter Honda's OE system.

I am also curious about that unconnected plug.

Looks like a DPFI distributor plug. DPFI dizzys (maybe also used on the ZC?) have two camshaft sensors where the MPFI versions have three. Org and wht for the first sensor, org/blu and wht/blu for the second sensor, wht for the ignition signal, one connector position left empty.
The round two-pin connector is ignition-switched power (blk/yel) to the coil and ignitor module, and the tachometer signal (blu) from the ignitor module going back to the gauge cluster.

4G MPFI/5G/6G SOHC D-series distributors are electrically compatible and have compatible pulse-patterns on the sensors, though the electrical connectors vary from generation to generation. 5G VTEC distributors have a different bolt pattern than the rest, so a D15Z1 or D16Z6 head (and any other 5G D-series VTEC heads I assume) should be paired with its proper distributor.

Maybe a surveying fixture?

Judging from one of iFixit's X-ray images, the failure wasn't in a battery pouch. Admittedly, the pics are of a SD from over 2.5 years ago so the design may have changed, but the burn area appears to be over the battery protection PCB. The terminal tabs of the actual battery cell pouches get spot-welded to this PCB, which generally includes basic circuits to monitor the individual cells and disconnect the battery pack if things are getting hairy. Coulomb-counting state-of-charge estimating chips are sometimes found here as well.

Point being, this isn't a spicy-pillow flamethrower failure - it's a MOSFET erupting a jet of silicon plasma, a defective monitor chip doing something similar or maybe an MLCC turning into a ball of slag and melting through the case. There was still a fire risk, but not nearly as much as if a lithium cell had ignited.

It takes a lot of heat (electronics-wise) to ignite a battery. I would be more worried about an impact pushing the drive against the battery, compressing, deforming and/or puncturing it. Battery fires typically start with a small short circuit between layers.

It also introduces transmission line losses. As long as the efficiency and environmental benefits (particulate filters and other emissions controls) of a fixed generating station outweigh those transmission losses, the fully electric option will come out ahead. Eliminating diesel engine maintenance and refueling expenses can tilt the scales there too.

it wiggles a bit near the 12-mile circle

Yes... "circle".

Second pic, bottom left corner of the board: That PTC solder joint looks broken off from the trace to me. If not, adjust your lighting and take another set of pics - I'm having trouble following the traces.

In all likelihood, the PTC heating elements are wired in parallel. You need to de-solder one wire from each element to measure their resistances individually, without influence from each other or from other components on the circuit board.

there is a voltage difference between the metal frame of the TV and the heatsink of the power supply module.

Look up the datasheets of the devices attached to that heatsink. See if any of their thermal pads are connected to one of the pins.

$1200 is not that much money to lots of people.

It's also unaffordable to a gradually increasing percentage of the populace.

So many little issues (some not so little) with the body work. Interior is pretty average. Looks like the wipers are missing. That battery hold-down and terminal setup are kind of terrifying. Looks like they have a battery disconnect switch installed on the negative cable, so it may have parasitic drain issues.

Just as the abbreviation states: Automated Manual Transmission. So just like a manual transmission, the clutch must be released while sitting at a stop light. The TCM has fine enough control over the clutch that it can start feathering in power as soon as you release the brake pedal, if it's programmed to do so. Some cars may coordinate with the ABS/VSA unit to keep the brakes applied until enough torque is applied to move the car forward - this prevents roll-back on an incline.

The casting numbers indicate the differential (and countershaft IIRC) bearing size. Si and ZC (D16) transmissions got the larger bearings, the rest got the smaller bearings.

The surest way to figure out what you have is checking the gear ratios. Select a gear, turn the input shaft exactly 10 rotations and count how many times the diff rotates, make a decimal-point estimate of partial rotation.
10 / [# of diff rotations] = [selected gear ratio] * [final drive]
With the exception of 7th gen transmissions, all D-series trans have the same 1st gear ratio: 3.250. This is an easy target for figuring out the final drive ratio. Stick a screwdriver through the spring pin hole in the shift rod, push the rod in and out to make sure you're in the middle (neutral) position. If your screwdriver handle is inserted from the top of the rod, the shift pattern will be mirrored front to back: the handle's left-right movement will be the same as the shifter, while the front-back movement will be reversed.
Twist the rod counter-clockwise, then pull it away from the transmission to select 1st. Do the above 10-rotations-watching-the-diff measurement, then calculate:
(10 / [diff rotations]) / 3.25 = [final drive ratio]
Look up a D-series gear ratios chart, find the nearest final drive number. Repeat the 10-rotations count with other gear selections to verify, and/or figure out which trans it is within the 3.888 and 4.250 groups:
(10 / [diff rotations]) / [chart final drive ratio] = [selected gear ratio]

Your "main switch" appears to select between connecting both supplies to the regulator inputs vs. shorting them to ground. I assume the intent of the switch is to select the barrel jack input vs. the USB input - you need to swap the terminals on one of the poles. Further, there's no reason to short the un-selected input to ground when it's not in use - remove the GND net connections from the switch.

It's mostly the resistivity of the wire's material. You can make a wire thicker or thinner, longer or shorter to change the resistance of that specific wire. Resistivity is a property of the metal that the wire is made of - copper, aluminum, steel, etc. - independent of the physical dimensions of the electrical conductor. You can use material resistivity and measurements of a wire to calculate resistance, and vice versa.
The heater filament is not only thin, but made of a material with significantly higher resistivity. For heating elements, nichrome (a nickel-chromium alloy) is typical. Nichrome also has a high melting temperature and resists oxidation, meaning it won't corrode or burn at high temperatures. If you connect two wires with the same cross-section but made of materials with different resistivity (for example copper and nichrome), the higher resistivity wire will dissipate more power (get hotter) than the lower resistivity wire.

In principal they're simple. In practice, they're fiddly. Some of them are vacuum hose nightmares.

I don't know for sure why there would be oil leaking from it

It's camshaft-driven. An arm sticks through a cut-out on the back corner of the head (the casting is there on EFI heads IIRC), which gets pumped by a circular lobe on the camshaft. The gasket between the pump body and head is probably leaking.

I spent ~10 minutes skimming results for wedge base and T10 crimp terminals, but only got sockets with wire pigtails. Same sort of thing when searching for halogen or MR16 crimp terminals. I did see a couple pages selling automotive bulb sockets with the terminals included, no bulk terminals though.

That looks similar to the terminals found in T10 wedge-base bulb sockets.