First of all, if you haven't done so, go to this thread and download Ed's manual for Vegas/Axis units:
On our unit the interior light switch is mounted near the counter top (there are two sets of switches on ours a higher level one and a lower level one). The higher switches are for the interior lights and the exterior light, the lower set is the store/use switch and the awning in/out. If your interior lights are on the lower set they are wired wrong...
For general maintenance you can use whomever you wish. A Ford dealer will change the engine oil but won't touch the generator (at least the Ford dealer I spoke with). Onan/Cummins told me they would do both (e.g. the generator people). Call around and get the best price.
That device is a 100 amp breaker. If you see a yellow "flag" or arm sticking out the breaker tripped. You push the arm back in until it clicks to reset it.