1) I think you'll probably find that the door panels might be the easiest place to mount the tweets... If you're going to do a dash install I think you want them firing up at the windshield... Sail panel install looks clean - does anybody know if sail panels from a coupe with the tweeter mounts will fit a 4dr? In terms of audio fidelity, apparently a kick panel install is your best bet.
Q-Logic makes good products that are colour-matched to your interior
2) Mount the crossovers in the door panel... Just find a location out of the way. There`s lots of empty space in there. I wrapped mine in some foam and then plastic to ensure they wouldn`t get wet or rattle around.
3) You`ll want one of
these. You`ll probably want one of
these as well.
4) I didn`t use any dynamat in my install and I have zero rattle from my doors. I don`t know if it`s really worth it.
5) Remove all interior panels that run along the sides of the car - your kick panels, etc... I think with 7th gens people usually run the power cable for the amp down the passenger side (battery is over there and
there`s an accessible hole in the firewall) and the RCAs down the driver`s side.
6) I just realized you used 2) twice... anyhow... Other than the above links,
this might be of use (removing door panels),
as well as this (removing factory stereo)...
But this is definitely the best document you`re going to find - it`s Crutchfield`s install document for 7th gen (covers coupes and sedans).
HTH.