22 year old confused and would like advice

[Tracy C]

4) Any way to tell if this just a maturing hairline versus propecia shedding?

If you are a caucasion male, it is most likely that you are developing your adult male hair line. I am reasonably sure that there is nothing a male can do to prevent developing and adult male hair line - because this is a normal male trait like bigger hands, bigger feet, deeper voice and so on.

2) How possible is a hair transplant for the temple region, and what are the usual grafts required?

It is possible. Doctor's do it for transgendered patients. However, most ethical doctors will not do it for a male who is not transgendered. Because the risk of surgery outweighs what little percieved possible benefit there might be - and it is usually a waste of grafts.