When doing something like this, I not only bag and label everything, but I take cell phone pictures, so I can see how it was together before I took it apart, to help me put it back together the same way.
Excellent strategy when taking something that complicated apart for the first time.
That quick change gear box will keep you busy.
When you get finished, you'll OWN that lathe. You will have done your aunt and uncle proud.
The dinged up oil cap on the headstock is likely some sort of Gits oil cup. No big deal.