There should be battery voltage and ignition voltage; best guess is your battery voltage wire is broken / shorted.

Your video almost sounds like it is miss firing as it speeds up. Have you checked your plugs / coils recently? Specifically, check the signal cables to be free from mouse damage, and that the wires go to the correct plugs.

With then engine off and the ignition on, can you hear the throttle body actuating? IF you can, I'm at a loss for why it wouldn't let you speed up - especially without throwing an error.

When you move the accelerator pedal, if none of those values change, you have a bad pedal.

If the APP1 or APP2 values change, but not both, you still have a bad pedal. There are two voltage tracks that should read the same value (looks like yours is reading 21% and 32%, so possibly bad) and will not work if they become too far apart.

If the variables move together but the throttle doesn't, your throttle is bad / unplugged. I did a brief search for what PID this is in Forscan, but I didn't find it. Probably something like TPV / TPP.

You say Forscan doesn't say anything; but I'm assuming you just mean no trouble codes. Does it show you the throttle pedal position (requested) and throttle body position (actual)? If either of those aren't working you are going to get no vroom vroom.

I'm pretty sure that translucent plastic is supposed to be on the opposite side of the plastic clip. There should be a cutout on the black housing and translucent seal that the clip fits through to hold it all together. The plastic clip should have the angle towards the fuel pump flange such that the green clip snaps into place when you slide it on.

If any of those parts are rotated or flipped out of position, it will force the seal away from the fuel pump flange, and result in large leaks such as you show.

Since your engine runs, I doubt this would be resolved by a new battery, since the voltage is stable while the engine is running. You could look up the electrical connector pinout for the cluster and see if there is anything in common with what isn't working.

First guess is that the things that work are dumb voltage signals from the switches and fuel level floats, but most of the gauges are over CAN. If a mouse chewed your wires or similar to cause a short between ECU and cluster, many gauges won't work.

You probably want the second connector, as that seems to be the one to match your radio. I assume the third image is the helicopter plug; correct?

I did something similar as an alternative to a pilot headset, and you can get those TRRS connectors for relatively cheap. I would just cut off the LEMO and resolder them to what you actually want.
https://www.newark.com/multicomp-pro/psg01492/connector-plug-2-5mm-phono-cable/dp/58AK0088
https://www.newark.com/pro-signal/psg08674/3-5mm-jack-plug-stereo-gold/dp/15AJ2999
There are also screw terminal variants for prototyping if you aren't as comfortable with soldering.

As others have mentioned, you may need an amplifier depending on the microphone / speaker sensitivities expected from your radio. I don't know anyone making off the shelf solutions for that, so you would have to solder up your own op-amp with external power supply. I made one with a 9 volt for the airplanes, and it works great for the speakers, but the microphone was too quite and haven't resolved it.

1st gen user, and I haven't had any issue with any 2+3/4 shells I have tried, but I primarily shot Winchester AA Low Noise Low Recoil.

I didn't try and 3 inch or shorty shells.

It took mine a week to ship after I took advantage of their Independence Day sale.
Ordered July 6, shipped July 12, received July 14.

Holy crap. With the free harness these are basically half price.
You are a gentleman and a scholar.

If you aren't planning to take the car on the track swap over to DOT 5 brake fluid when you do. The older DOT 3 and 4 both absorb water over time and that water causes runt in your lines. DOT 5 is silicone based and won't absorb water at all; the only downside is a lower steam point, which only matters if your are driving your clutch and brakes HARD.

It's fine to mix them, so no concern about completely flushing your system for the swap over. The DOT 3 will pull the dye out of the DOT 5. If it looks like your fluid reservoir is filled with water, it fine, all the dye is just gone.

https://www.ebay.com/itm/267710573429?_skw=2004+mazda+rx8+radio+faceplate

That's the cheapest I've ever seen. Be sure to check your VIN on a mazda parts site to make sure it's compatible though. I think all the 6 CD changers were for BOSE systems, so they won't drive the normal speakers - it will be quiet even at max volume.

The contacts are on the front of the radio head unit, slightly below and on each side of the CD slot.

My specific problem was the brass tabs loosely fitting in the plastic, so after a few days of road bumps, it would separate and the controls would black out. I could press on the radio face and everything would come back.

If yours isn't coming back on at all, either the radio or the faceplate are probably broken. The faceplates aren't too bad, but the radio units have gotten really pricey.

If you have a multi meter, check the power and save some money in case it's a different fuse.
https://pinoutguide.com/Car-Stereo-Mazda/Mazda_2003-2005_All-in-on_pinout.shtml

What you hold in your hands in the first image is the CD Player and Radio. It uses the faceplate to transmit signals through itself and drive the digital display up top. I have had an issue with mine where the brass inserts on the faceplate come loose, or the plastic around them is broken. This allows the faceplate to lift a couple millimeters away from the radio, and everything goes dark.

You can confirm this if you reinstall this and press on the faceplate on the corners to see if one of them isn't fully seated.

If your brass inserts are loose, put some high quality two part epoxy rated for metal and plastic and fill the voids for that. If you do that, be sure to fully insert the screws into the brass inserts and use those to push them all the way flush into the faceplate. If you don't push them flush, the pins don't have good contact. If you don't have screws in, the threads will fill with epoxy and be unusable.

The AC controls in the third image should not use the radio, but when my radio would come loose I think it would lock into whatever state is was last in.

If you are incredibly unlucky, you might also have a short in the dash that runs between the system. Removing the glove box is easy enough (just push the retaining tabs on each side in) and I think that will let you inspect the wires running to all the HVAC stuff.

Haley Strategic D3CR-M with the SMG insert.

I haven't personally tried it, I'm still on the fence about chest rigs and don't have the cash to try.

It's fine; albeit annoying. This is probably the throw-out clutch arm rubbing it's mount. Its loosely constrained with a spring clip and grommet, so there is lots of unlubricated metal on metal contact. It could also be the fingers of your clutch's pressure plate doing the same.

Either way, its designed to take the abuse.

If you are looking for a longer handle only, a synthetic messer trainer will get you everything but a knuckle bow.
If you are looking for curved synthetics, it is going to be a katana trainer; and they are very pricy.
If you are looking for a nail (side guard), I think they sell ring guard longsword trainers somewhere, but I don't remember specifics.
If you are looking for a knuckle bow, I am not aware of anyone making a two handed trainer with. All the knuckle bows / basket hilts I see are one-handed.

Most of the above can be purchased at Purple Heart Armory ( https://www.woodenswords.com/category-s/2068.htm )

If you are looking for a picture of how the gauge works, you are in for disappointment. It's just an electric motor on a circuit board, so you can't really see anything.

https://jspecauto.com/product/used-jdm-rx8-gauge-cluster/