Will, I'm not sure if I agree with you for #1. Considering most ff import cars have less than around a 115 amp alt to begin with, I believe adding a 100 + amp draw will strain the electrical system pretty badly. But now that I look at it, are you sure those fuse readings are correct? A 200 watt amplifier having a 40 amp fuse on it? If the amplifier is 100% efficient (which of course it is not),
power = current x voltage
200w = I x 14.4
I = ~13 amps

Since its not 100%, it is probably alittle higher, say around 20 amps. Seems kinda strange. Seems like the MBQ's fuse rating is high too. At any rate, assuming the fuse ratings are correct, you will need to have an inline fuse rated above 130 amps. ANL fuses go all the way up to 300 amps I believe, so you should be fine. And no, do not use a circuit breaker. While some people use them and claim they work fine, I would not use them. In an under the hood environment, its been tested that the majority of circuit breakers take too long to open.
For 130 amps, you could get away with using 4 gauge wire, but do not put a fuse on that is more than 130 amps. You always choose your fuse according to wire size first, meaning don't put on a fuse that is too big for the wire, else it is useless. 4 gauge wire can handle up to 125 amps fine, but you will probably not draw that much current anyways, so you will be ok with 4 gauge.