s3nt3nc3d is correct. Most all power amps have 12v remote lines so hooking both the positive terminal and the remote line to the positive post on your battery and the negative terminal to the negative post on your battery should turn the amp on.
A good way to test the amp (with the woofers) would be to use any type of coarse conductor wiring rated for electricity. I use a stiff 10 gauge stranded copper to power my 1200 watt amp with an 80 amp DC circuit breaker at the battery and i've never had any problems. I also use a stiff 12 gauge stranded copper to connect my amp speaker leads to my woofers. (I have 2 kicker 10s). Just make sure you don't use solid conductor wiring for power or speaker output as the dynamics of this type of wire aren't suited well for car audio.
It might be a bit of a waste of wire to cut short lengths for testing purposes, but if you have it laying around it works, so why not.
Be careful though because chances are if the wiring was rusted, the power amp may have came into contact with moisture / water at some point. Without a circuit breaker or fuse (assuming you're not going to use these while testing) be aware that the equipment has a possibly to short out and that might cause an electrical fire in the amp, or the power wiring (and at the very least you might get some nasty burns).
So if you're testing it with leads to the battery, make sure to use fuses in the hot side of the circuit that appropriate for the amp, or keep the leads where you can disconnect them quickly (touching them to the battery post should be enough to make the amp turn on).
To see if you have audio, you can easily find a mini-plug to stereo RCA adapter cord that will allow hook your ipod / MP3 player up to the amp to play a song as a test. Make sure that before you make any adjustments on the amp (gain or LPF) that you have it installed, working, and hooked to the head you're going to use as the levels of the audio coming from your test source will not be the same as those coming from the SW outputs on your head unit.
Hope this helps.