1. Which Belt Mountain base pin and latch system should I get?
Go to the Belt Mountain website for information. You can call or email Kyle and he will answer all your questions. Email responses may take a couple of days because he might be working at his other job.
2. Can I use just any old car wax? I haven't had a revolver that isn't stainless in a number of years. The manual from Ruger suggests I could put a thin coat of wax on it to protect the bluing from skin oils. Sounds like a good idea.
Renaissance Wax works good for this application. It is available on Ebay and a small can will last you for a long, long time. Firearm museums use it and highly recommend it for firearms.
3.How long for the factory oil to cease and desist with the staining? I am halfway inclined to take the pins out and take the thing completely apart to clean all the old oil out of it.
As an alternative, you can use Gun Scrubber or non-chlorinated brake cleaner to get the grease out of the gun. Follow up with a good lubricant and preservative. I like G-96 in the spray can.