Next time you are at a campground with full hook ups you could do the flushing by just filling up the fresh tank and using the pump to pump it through your lines at all of the faucets and then letting it run to the sewer through the grey tank.
Camping world claims that they will help with a walk through of your RV (small fee I believe). That way you would get to see how your appliances work and they may have someone who could walk you through the solar you have also.
RV repair places are were most people go for all of the stuff you mentioned, but remember that some parts of your RV can be worked on by a regular appliance repairman (air-conditioning is air-conditioning, but a home repair guy might not want to get on an RV roof) and may be cheaper or at least more convenient than taking it somewhere. Also there are mobile RV repairmen who might be easier to deal with also
