We had two guys at my last command who had each ejected twice. One guy was from VF-41. CS 'Bru' He was featured on one of those 30 minute news programs (Inside Edition?)...cant' remember the name. The girl doing the interview also got to fly as part of the interview package. Oh my, there was certainly some eye candy there.
The other guy....I was giving him a tour of the TG building. Lining the walls are dozens of pictures of A/C...he stops, then tells me that (pointing) 'that one doesn't exist anymore; I dumped it off Cubi.' He went on to tell me that he woke up under water and, after a year in the hospital, decided to do something else. He became a flight surgeon.
There is no magical number for ejections....if you clear the physical, you get to continue flying. As far as being shorter after an ejection, I have never heard of someone being measured after one....in theory it sounds good as the joint space between the vertebrae will always compress during an ejection; they will also rebound back to very near their normal size.