you can do either inside or outside to run the wire. sometimes easier to go outside, especially with multiple runs. i did mine inside, and under the carpet. terminals is up to you i guess. i dont like the push kind, so i just used bolts. you could even just run a straight wire through there also. and yes grounding the outer ring of the RCA will help reduce/eliminate noise, but it's not the sole solution, tho it will help determine if it's coming from somewhere else.
those dont answer all your questions...but just some help. and x3 on that. not a bad idea. there's a lot of stickies in each category also with useful info
EDIT: the search is kinda hard to use sometimes imo. minimum of 4 letters. unless there's somethin i'm not seein