ABOUT CACHE AND P2p limited

hey all
i just wanna 2 try mikrotik but i have some questions??
1 -HoW I CAN LIMITED P2P conn 4 users ??
iwanna script 4 it or some one Explain with pics
2 - any pc that iwant 2 make cache in mikrotik example
RAM = ???
Cpu =???
MHZ = ???
last one
3 - if i make Cache what size i can let him to store into cache?