pptp on RB1000

Hi,

I have bought my RB1000 and set it up as a pptp server for remote users.
i want to restrict access of pptp user1 to a specific server ip and ports ?
how to protect my router and my internal LAN without affecting the pptp users access?
is there a book that teach and show tutorials for configuring mt routers via winbox?
UPnP if enabled on all interfaces will it affect security?

thanks,
SAM