When did you get the ban? Maybe it was when kids on reddit were spamming posts about high ranked accounts botting their skills?
Getting perm banned from agility when you have 1650+ total and several 99s is definitely not normal, are you sure you got banned for botting agility?
Doesn't take that long if you've got motivation to play the game, depends how fast you get the reqs etc too.
I botted probably ~20 hours within 2 days, which is stupid. I didn't realize i had botted that much.
Not couple, i'd say the more quest points you have, the better chances.
I had 46qp when i got banned if i remember correctly.