Well I don't have particularly high expectations of myself so I'm not sure how I'd define 'issues'. :) For me the dexterity is a learned skill just like memorising the chords/notes.

I think very young people might have an advantage in how quickly they gain the required dexterity. However I've usually associated a young person's ability to learn the guitar quickly with the fact that most young people have a lot of free time on their hands and they just spend a lot more time practising than a busy adult.

Unless you've got an explicit ailment (eg arthritis) I don't think age is a barrier. "Working man's hands" might slow you down a bit at the start. I guess I'm lucky to have "programmers hands" :)