It's mostly genetic. How tall are either of your parents or grandparents? if they are 6' 8, then it's possible. Even if they aren't, it's possible but very unlikely. Being 5'8 at 14 really doesn't tell us anything about how tall you could become, some people spurt at different ages.
Unlikely, but I think 8-10 inches might be possible. Try getting enough to eat in general plus pumpkin seeds. Vigorous exercise like fast running and swimming too, but not heavy lifting.
Maybe.. But it'll be extremely rare. Let's reach for a plausible goal like say 6'0", for starters.
i'm sorry but i dont think thats possible...thats ALOT of inches to grow.
it could happen, will it ? probably not :)