Everything you said will for fine.
-no don't use rubber grommets or springs to add "shocks" to the drive.
-extra fans are always a good thing, I like to find the quietest possible <21 dB
-"hard wire the lcd and psu".. sinch, just like wiring an amp or lighting
-Rca to amps is just fine. Some people get that hauppage TV/FM tuner but the TV reception does not work well in a car.
-Copilot and Street Atlas are two of the best gps softwares out there. I don't know about speed camera alerts though, its a GPS not a miracle software.
-Make sure you have 2x the amount of money you intend to spend before starting