1. the pico psu only accepts a 12v input. so it will not work in a car-- when a car is running, its voltage can vary from 5-15volts. check the m1, or m3 for a similar form-factor power supply..
2.wintec ssd--no comment-- i use a ocz vertex, but i knew ocz was a good brand, so didn't research past that..
3.screen and backup camera-- many will get a screen with a reverse wire input-- so when there is 12v on that wire, the screen will auto switch to the input where the camera is plugged in. don't know of many other solutions..
4. i cannot find any info on any usb dongles that specifically state that they can be used to create a adhoc network.. i have had 3, and none of them did it(a el-cheapo, a hawking technologies, and now one with a via chipset-included w/ the zotac 9300-wifi board..) however: the netgear pcmcia wireless adapter that i have will do this-- i haven't tried it, but i remember it is in the settings..
4.5. maybe i ought to start a poll, but i don't know if 802.11n is worth it yet for most areas-- it is a faster speed and distance, but it is also more expensive, and AFAIK, most hotspots are still only b/g, so it might not be worth it..