Gen II upgrade questions

Hello everyone.
I have been studying repairs from these forums for a long time and have made a few upgrades from suggestions on here.
Now I need some help as I can't find the answer here, so I got the nerve to ask for some help.

I have a 2004 prius with 296k miles on it, and it has the intermittent display errors in the combination meternot turning on. I want rut fix it, but also want to not have the fixed meter stop at 299999. So bought a used combination meter from a 2008 prius on eBay, as, from what I found so far, the 299999 freeze won't happen.
I installed it today and now have a new issue.
As you see in the photos, I had almost a full tank of gas when I started to replace the meter. After I was done, the meter shows flashing empty.
Any thoughts on why it wouldn't recognize the gas being almost full? How would I fix this?


On a thread from Toyota, they say that the miles are stored in the memory on the "computers" on the side of the combination meter and it should be programmed by the manufacturer with the current millage. Question is, can anyone else program the miles on my "new" combination meter?

I replaced the clock spring under the steering wheel to get back the functionality of the buttons on the wheel, but the airbag light didn't go away. What else do I need to do?

Side projects:
1. You will notice the TPMS light is on. I don't have the sensors installed on the rims yet, but I wanted to do this a few years ago but didn't look into how to add the receiver which the sensors talk to, so I didn't install them. What receiver or ecu will I need to get internet to utilize the TPMS feature of the 2008 combination meter I installed?

2. I have the keyless entry fib from this 2008 and a few of the receivers from the door handles, which are installed, and the one for the back hatchI which I will install later.
The question is, what other receivers/electronics do I need to make the keyless entry work?

3. I have the back up camera from this 2008 as well.
I can cut a small hole in the hatch to mount the camera properly.
The power can come from a splice in the reverse light instead of getting the wiring harness (but I would rather get it used, as it's easier to snap in the connections). Where does the video feed from the camera need to go to make the back up camera function?

4. Has anyone added navigation?

5. Has anyone added rear air conditioning through the center console between the two front seats? I would remove the cup holder to make space (as my kids have cup holders in their car seats anyways).


Thank you in advance for your help!
(If the pictures don't load, sorry. I'm trying and I'm new. I don't know if they didn't allow pictures from new members)

 

Thanks for the response.
Just so I understand what you are saying, how would the DMV help for the odometer reading?

 

Update: I was trying to find an answer to solve the gas gauge issue, but I had to get somewhere. So I drove my car and after half a mile the fuel gauge started working, and shows half full.
It's better than flashing empty...