Welcome, Carm & congratulations on your purchase. Never be afraid to learn new things, even the scary stuff like electrical and propane. We have several books on RV maintenance and
12V electrical. I will PM you later with the titles/authors so you can start some research. If you do some digging here, you might find an experienced owner in your area who can look at your trailer and give you a list of projects you should tackle first. They might even be willing to give you some hands-on assistance with more difficult projects. A young couple we've been helping here in our area, found us through the forum. You definitely need to evaluate if your small projects will have to be undone to complete the big projects. If there is any water damage in your trailer, it's a good idea to start there. Water causes a lot of problems with all kind of things from the subfloor to the electrical. Not to mention there could be moldy insulation. Not a safe environment to live in.
Please forgive me if this sounds preachy. Did you get a title with your trailer? It's not uncommon for older trailers to have their titles "misplaced". If you have the title, you're off to a good start. If you don't, contact the seller to begin tracking it down. If they are the last title holder, it's much easier for them to contact the state and request a copy. For a trailer that's been sold repeatedly without a tranfer of title, it's far more difficult for a new owner to get one. A bill of sale won't cut it in this situation. You would need to contact your state and find out what steps you have to take.