On relay location...personally I put some in the engine bay and a couple under the dash; just depending on what they were feeding.
Putting them in the engine bay keep the long runs of wiring going the back for instance dead when ever the relay is not energized, instead of having it hot all the time.
If your wiring is run properly should be an issue, but figure it can't hurt. And looking at late model cars, they have the bulk of the relays in the engine bay near the battery and mayb just a couple in the dash (same for fuses..the bulk of the high amp ones in the engine bay and the lower amp ones for interior stuff inside the dash)
Just the way I do it anyways..
(car I am doing now...I have added fuse blocks under the dash to control the interior accessories, and will have all the engine control stuff in the engine bay I figure)
PS. Here was last last little project..abit of wiring in it to play with
http://www.cardomain.com/ride/2682662Alot more from scratch in my Torana so far...
