I have a '95 Dodge SMB so our setups may be similar. Regarding the electrical question, on mine, I have an inverter that is connected to 3 AC panel breakers. 1 breaker is the main, 1 breaker is the passenger side and 1 breaker is the driver's side. If I am on shore power(electrical cable plugged into the side of the van) I flip on all 3 breakers and I have power to all my outlets, my microwave, and my fridge runs off of 110v AC. If I am running on 12v DC then I need to turn on my inverter, then I have to flip on the main AC breaker, then flip on the breaker for whichever side of the van I want to use the outlets on, or just flip all 3 breakers on to have all outlets in the van working. They key idea here is that the outlets are AC power only and therefore you need to be supplying AC power in some way, shore power or inverter.
Here is a picture of my inverter, yours may be the same:
There is a button on top of the inverter that can set the inverter to be on or in charging mode. This is the button I have to hit in order to get AC when I am not plugged into shore power. I happen to have a remote cable that is run from the inverter to a button elsewhere in the van so I do not have to get under the gaucho to access the button but you may or may not have that remote button.
As far as my "Radio Button" they installed a toggle switch in the dash right next to my radio for that purpose. Here is a pic:
In the down position the radio runs off of the van starting battery, in the up position the radio runs off of the house batteries(no key in ignition needed, just flip the switch and radio turns on.)
Hope this helps and welcome!