Like Chuck said, a fuse can look good but still be bad. Something else to check would be the connections going from the fuse panel to the wiring. Make sure all the wires are secure on the panel, and not corroded away.
The breakers are for 110 VAC, while the fuses are for the 12 VDC circuits. If some of the 12 volt
stuff works, then you know you're getting 12 volts to the fuse panel from the battery (or the converter if you're plugged into shore power).
Do you have a test light, or multimeter? If not, might be a good thing to buy at some point. You can pick up a cheap one - you don't need anything fancy for checking fuses and voltage.
If you need some verbal help checking things out, give me a call.