The way you phrased your inquiry about the toilet suggests that it may be a recirculating toilet. Our first trailer (1972 model) had one. You 'charged' it by putting three gallons of water in it, added the enzyme powder or liquid and recirculated the water over and over for flushing. Every few days or at the end of the weekend, you dump it.
Of course, if all you're asking about is the enzyme to break down the nasties in the tank, nearly any RV supply or campground store will carry several different types, powders, liquid, tablets. They all do the same job. There are directions for use on the packaging.
As stated above, check the outside door to the back of the refrigerator. Many of the older ones were 'three-way', Ac or DC electric or propane. If your's is like that and it works on DC but not AC, it simply may not be plugged in. To use propane, you have to open a small access hole to get to the pilot light.
A 33 year old fridge is not going to cool very quickly unless it has been serviced regularly. It's old. It could take a few hours, especially if it's hot outside.
I second the suggestion about changing out the propane regulator. A fairly simple and inexpensive job.
BTW - those old Prowlers are heavy by today's standards, but, they are pretty stout. They were a popular rig in this neck of the woods through the 70's and 80's. If you've got one that's been even moderately looked after, it could last you a long time.
2011 Flagstaff 831FKBSS
2007 GMC Sierra 1500 Ext Cab, Vortec Max
Prodigy, Reece DC