Your gonna want to get at least ten feet of speaker wire for the crossover to new tweeter connection. Using the old speaker wiring is fine if you must but new wires will be pretty easy to run once the panels are off. Just sayin. lol
You'll want the usual 20 gauge electrical connectors as well as some butt end connectors for the harness connections. You'll also want a 9v battery to test phase before you hook each speaker to the head unit. You hook the + and - speaker wire to the + and - of the battery. If it's in phase(polarity is correct basically) the cone on the speaker will push out. You want to make sure all 4 speakers are in phase. If one's not it's easier to reverse the head unit hook up then remove the mounted speaker.
As far as dynamat goes, it is so, so worth it. I know you have other priorities but when your ready just set aside a day and do the doors and drivers foot well at least. Also, don't buy dynamat. It's just over-priced butyl that has a cool name. There's some stuff I got from Amazon that's as thick, as sticky, as good, and 1/3 of the price. I used those savings to put in those fancy Infinity speakers I linked you to. lol
As far as the back up camera goes, the unit you buy will have all the wiring. It's easy enough to pull the head unit back out to hook up power, ground and feed. I'd just hold off until you have the unit.