I'll try to answer here, I'm more of a Task Force guy.
1, the switch for the brake lights (I beleive is the same as TF), The arm rides on top of the brake pedal arm, when the pedal is depressed, it releases the switch arm (It's spring loaded) making it contact.
2, the hater is grounded through the heater housing.
3, One ground cable should go to from the battery to either the cab or chassis, preferrably the cab, the other goes from the engine (starter bolt is a good mounting point) to the same cab/chassis mounting point as the other cable. It serves as the engine ground.
4, unsure about the retainer, i would think that it would be included with it, again, I'm not 100% familiar with the AD trucks. Wiring is relatively easy, 1 wire ran to a power source, usually a constant hot. If you're only going to loks, no wiring needed.
5, E-Bay or the swap meets. Also, check out the Swap Meet forum. The radio block off isn't being reproduced, but you might be able to get one from someone that is installing a radio in theirs.
