I just got a KnuKoncepts 4AWG kit and it came with the wires etc. and then a baggie with a bunch of gold tips (circle things)... I was wondering how you attach the wires to these things? Should I solder them? Should I crimp them? If I don't buy a crimping tool, is there a suitable replacement (vice grips/hammmer,ect).
It depends on the design of the ends. Normally power connectors are just crimped, whereas data connectors are often crimped and soldered. While vice grips/hammer can crimp in an emergency, it's not going to do a proper crimp. You really want the right tools doing this, especially in large gage wire (which can obviously carry a lot of current). I'd recommend picking up the Haynes Electrical Manual as a reference. http://www.amazon.com/Automotive-Electrical-Manual-Haynes-Techbook/dp/1850106541