The components are listed in my signature and are currently being shipped to me.

My plan is to keep the amp under the seat(there is an existing 2-channel amp there that im replacing), have ipod cable run from HU to the glove compartment, then subwoofer is naturally in the trunk on driver side.
I have a lot of good 16 gauge speaker wire that i got from Monoprices for my home theater and i believe it should be sufficient for the door speakers.

What kind of other cables would i need and what length should i aim for?

I prefer to avoid Monster and other flashy brands and stick to places like monoprices whenever possible.

 

4 gauge power and ground wires, rca interconnects from monoprices (or knukoncepts), and maybe some 12 gauge speaker wire for your sub.

 

like he said ^^^

but you don't need 4g, 8 will do fine, as well as you don't need 12g speaker wire

but like i said you don't need as thick of wire as stated above, but it doesn't hurt it either

 

generally speaking, how long would the 4g power/ground cables need to be my amp will be under the driver seat and the sub will be in the trunk on the driver side?
I guess i could go home and measure, but if somebody has an idea, please do share.

 

for your amp i believe alpine recommends 8 gauge for power and ground.

alot of times you can find an amp installation kit for cheaper than buying wires and fuses separately. the wire in the amp installation kit will be plenty long enough.

edit: just read the part about you wanting to install the amp under the seat. from an amp installation kit you will have twice as much power cable as you need.