ok, lets see where to start.

don't want to connect the amp to a speaker, it should connect directly to the HEAD UNIT. Through an RCA out connector.

The cell phone sized thing was probably a fuse holder. they can get fancy, but they are pretty simple in design. You should definatly use one of those.

Something like this: http://www.crutchfield.com/S-9yj7r77...=711&I=211PS8B
would have pretty much everything you need to install it. Not bad for $35.

Hardest part is getting through the firewall for the power cable. 8 gauge power should do fine for that amp, I use 8 gauge on my heavy drawing 400watt amp and it's fine. Anything bigger is going to be much harder to run through the car.