Congrads on your recent purchase?
Analyzing the troubles from a description is like that commercial where someone drops off the vehicle and tells it makes a clunking banging noise when I do this and the mechanic just looks at them. Take it to a shop, show them the trouble, and have them look it over. It may only cost $20 or so or could be free, but they, being a reputable specialist, will give you their 'doctors' analysis. Then take it to another to compare their analysis. Getting ideas from the list is great, but from the sounds of it, it could be more than a driveway mechanic could handle.
Simple things like changing fluid can be done, and may provide good results. Noticing other related driveline noises is another result which an owner could easily fix.
I had a situation similar when wheeling 2 weekends ago. I was low on fluid and when at a steep incline, I couldn't get it to go when I needed. Adding fluid once on flat ground, I didn't have any trouble the rest of the day. Is the dip stick the correct one? Run it along the fill tube and make sure it reaches the pan.