Welcome to the land of Dodge van ownership.
Check your grounds.
But joking aside, these vans are notoroius for bad grounds causing bizarre electrical issues. And since you claim to be a mechanical Newbie, The grounds are the wires that lead from the battery negative post, to the engine, to the firewall, and there should also be one between the engine and the frame for redundancy. Cannot have too many.
The best thing you can do is get the factory service manual. It won't give any information about the camper conversion part of your van, but it will go into detail about the 1982 dodge van chassis. If you buy a Haynes or chilton, they cover dozens of years and you spend half the time trying to figure out if info applies to your year.
Here is the best place to find them:
This will be your best friend if/when you have an issue.
Since Class B camper vans are pretty heavy, you should make sure your tires are not too old, and are rated to carry the load. They should be at least D rated light truck tires, perhaps even E rated. You can check the age by looking closely at the tire. Somewhere there will be a 4 digit code. Like 3703. This means the 37th week of 2003. You should not really drive on a tire more than 7 years old, despite how much tread might be left on the tire. If you cannot find the code, it might be on the inside of the tire, so climb underneath and look
Your questions about the fridge are really too obscure to answer without more info. Do you know if it runs on propane, or if it is a compressor fridge that can run off 12 volts? Even propane fridges need some 12 volts to run the circuit board, unless they are very old. A propane fridge running on 12 volts will quickly deplete the batteries. A compressor fridge cannot run directly off propane, and makes some noise and vibration like your fridge at home.
If the fridge smells like ammonia, it is done, and needs replacement, or a new cooling unit.
For winter storage, you need to empty all of the storage tanks, and water lines and run a little pink antifreeze in them. You should either remove the batteries and take them home and put them on a float charger, or fully charge them and disconnect the ground wire.
IF the Van has rear air bags to help support the weight of the van, pump them up to the maximum PSI while in storage. Protect the tires from UV damage with tire covers.
Consider the furry tailed Ba$tards and other verminous rodents which might set up home and think your wiring is infused with peanut butter.
Now for the camper conversion part of your new van, you should find out if it was done by a company and try to find info about that company. If it was converted by an individual, you are at the mercy of said individual's IQ.
Some Sites you might find helpful:
And sign up for a picture sharing account. You are more likely to receive help if you can show the issue in a picture.
I use photo bucket, but there are many others.
About drinking in the back, it depends on the location. Having it registered as a motorhome definitely helps, but it really depends on the local laws, the cop, and the smell of your breath.
Welcome, and good luck.