I'm 5'0, 100llbs, will I make a good offshore/dinghy sailor? Also, because of my height/weight, is it possible that this could affect me negatively if I want to skipper?
Sounds like you might be talking about racing. I'm not gonna comment on that.
But if you are talking about cruising, it should not affect you at all.
I'll say this, when you are boat shopping you won't have to worry so much about head room and bunk length/width. I'm just over 6 ft. and it's a pain in the ass to find something affordable that is comfortable to spend time down below.
If I where a few inches shorter I would not hesitate to keep the boat I have.
Even more importantly, when I have to get into hard to reach places to do maintenance for fix something it can be downright uncomfortable. Being smaller makes things easier.