stereo install question, need opinions

Ok, I will be installing a friends amp and 10" sub into his car soon.Would 4 gauge power and 4 gauge amp ground be a good route? What is the general rule of thumb? Does bigger is better theory work here?Reason I'm asking is he got free brand new 4 gauge power and ground wire, so he wants to save some money by using this, even though it might be over kill.Second, His power wire fuse he says is a 8 gauge hook up, and doesn't want to buy a new one. It's never been used, just bought it when he thought he was going to install the stereo last year and didn't. He asked me if we could cut off some of the strands on the 4 gauge power wire to make it fit into the fuse holder.Is this safe? FYI fuse is I think a 60amp heavy duty.Connectors.Do we have to use high end connectors here? Will the regular ones you buy from a store work?Also, I noticed that the 4 gauge wires is pretty thick, how do we go about crimping the connectors? Can we solder then instead to the connector? I doubt we can solder tehm, but thought I'd ask...Lastly, What is a good size of wire to go from the amp to the sub. He has one 10" and that's it. Is bigger better in this case also?His wife doesn't like bass that often, and since they share the car, she wants a way to shut off the amp and sub. I suggested putting in a switch on the amps remote turn on wire so she can turn it on and off from the drivers seat?Need a quick response guys, prob going to do this this coming weekend.I know these are pretty amateurish questions, but he doens't want to spend any more money then he has....if it was me I'd buy the proper connectors and items to get the job done.Thanks

What is the brand and model of the amp and sub?

sub is a sony 10" xplod and amp ia a pheniox gold 4 channel, which he will use one side bridged. He will be using hi level inputs...

The 4 guage power and ground wires should be fine. As far as cutting the wire to make it fit, I really don't know. You can definately solder the connections, just be careful not to melt the wire covering. For wire going from the amp to the sub, 12 guage would work. The switch on the remote wire is a great way to cut the bass when wanted.

thanks bfog, I never used 4 gauge before so i'm not sure how i can get the wire to be crimped on the connector... I was thinking of instead of crimping the connector, just solder it onto the connector if i cna't get a tight crimp. I don't have a crimp tool. I heard that you can use a hammer and a chisel to crimp the connector.

Soldering is the best way to conect wires . (My way )