Is there a difference between wire used for speakers and wire used for a 12 volt socket or other 12 volt accsesories?
Copper is copper. Pretty much. More or less.
With stranded wire there are fine strands and course strands. There are also lots and lots of different types of insulation.
my plan is to run power to the back of the 4runner to an auxillary fuse block im thinking 8awg. Is that a big enough gauge?
Wire size depends on voltage drop, which is a function of load vs. distance. The longer and/or thinner the wire, the more the voltage drops *under load*.
To dump plenty of amps into a battery or a winch at the rear, then you want some seriously fat wire, but just to run a few basic loads, it's probably not necessary. #10 would probably be fine, since there won't be enough load to pull the voltage down enough to notice.
But yea, if you want to use #8, go for it. It won't hurt anything.
I was going to run postive and a negative to the fuse block. is that a better way to go or just run the negative from the fuse block to the chassis?
Best to run a dedicated ground. But also it needs to be kept right together side by side with the positive. The greater the distance between the two conductors of a circuit, the greater the chance of creating radio noise.
off the fuse block will be a socket for the arb fridge and maybe a couple extra outlets for other plug in stuff. to wire the sockets I was looking at 14/2 or 12/2 wire but it says "speaker wire". Is this the right wire to use?
Speaker wire will work fine as far as carrying the power. The only issue is the insulation. Often, speaker wire insulation is pretty soft.
Not that would much matter if you had proper fusing to protect the wires in case of a short.
Personally, I like something with a tougher insulation for power wires.