1. AP is provided by the game. the only limitation is that it will only generate 100 AP and stop growing (200 AP for VIP members). you can, however buy as many more if you desire. so, there is no real 'cap'.
2. while in the tutorial (and for a little while after)you are protected from attacks (unless you attack someone).
3. no, what you can amass during the tutorial is yours to keep and use as you see fit.
4. only for PvP combat (unless you want to attack someone).
5. there is no CAP for RP.
welcome to the game, the most important thing you can do at this time is finish the tutorial.
Thanks for the information!