For a micro bus like that, you're almost certainly running a medium-duty frame and suspension with some kind of 'one-ton' drivetrain. For the engine mechanics, you should be able to hit up basically any mechanic that works on pickup/fleet/work trucks; try to see if you can find out where the cable company has their vehicles maintained, if you can, or something along those lines.
For the transmission stuff, I would still use a transmission specialist.
For brakes, making the assumption that you're using hydraulic brakes, you could probably use the motor mechanic, or a brake shop that works on pickups. On the off-chance they're air brakes, I would go to a heavy-truck shop/stop.
For steering/suspension, you can try the local mechanic, but I would also check into a truck shop specialist, as guys used to 4000 lbs miatas and mazdas might not be fully conscious of some considerations with 14,000 lbs under the pedals.
For tires, you can try, but you're really just trying to find tires with the right load/ply- rating. You're not going to need any of the speed ratings, and you're probably heavy enough that the extreme traction stuff won't matter--though it certainly should be considered if you're not switching tires for summer/winter. But basically any tire shop should be able to manage that for your bus.
Inspections should be basic safety only, really... Since it's just another RV at the point you have it. Lights, brakes, honk the horn, done.