Coding the prestige system won't be that hard, I've already thought of a way. The rewards though I don't know.
Case ( whatever button we use )
If p.(server stat vars) >= (whatever the xp is for lvl99)
(Repeat above for all stats)
then
P.(new var yay) = 2
If
P.(new car above) = 2
Repeat and change the numbers.
( all that is for MY bulby 508, Idk about your server.)