1.) I haven't taken a starter apart in 45 years or so, things have probably changed?
The starters had motor brushes in them and they would wear, on small block chevy engines they were located on the rear end of the starter as I recall. It was pretty easy to take a length of pipe, wood, steel bar and put it on the back end of the starter and tap it while someone else was turning the key.
Back in the day you could buy a new set of stater motor brushes and springs at the auto parts store, they were easy to replace.