1. for a good budget screen, i got a lilliput eby701 off ebay. i dont really remember how much i got it for, but they can be had for around 150. or less if you get lucky. im sure your T/A has that same double din unit that i had room to play with. but my screen and pc and in seperate places, yet accessable. your bird definantly doesnt have the same room my blazer does, so a eby701 wouldnt be the best for your setup. unless you can fab a dvd drive somewhere in your dash.
2. that auto on/off is controlled by a startup shut down controller. i am using a carnetix p1900. it works perfect. you need to choose one that is compatable with your computer you will be using.
3. that startup shut down controller is made to use the 12-13.8-14.4v and turn it into the correct voltage and amperage for your pc. i have mine run off my stereo wiring harness. and no problems so far.
4. that is correct. use a radioshack (or from anywhere else) headphone to rca plug, and you are set. get a 4 channel amp if you want to control sound output on for seperate speakers. or a 2 channel with the LF and LR on one channel, and RF and RR on the other channel. dont do this on stock speakers either.
5. i do believe there is a T/A or F-body thread somewhere....
6. i am running XP since vista is too power hungry, expensive, and not reliable enough yet. for my frontend, i am running Roadrunner. it is the most open source one. or maybe the only. i dunno. my programming capabilities have never been any good. i do get lots of help on here. and if you can, get a meet going so someone could help you with a few programming tips.
hope this helped ya. i did spend at the most, $800 bux for my set up. but i just bought stuff and had it all set aside for me to put together when i had everything. i always looked for the best deal on what i was looking for. most, damn near all, came from ebay too. all this still seems pricey on a college budget. and it is. it will take you much longer to gather all the stuff up. i was able to because im military. but i still tried to go as cheap as possible. and i think i succeeded. look at my sig for some ideas.