If you haven't already done so, create a GPO and link it to the OU containing the terminal server. Use loopback policy processing to configure user settings:
You can add a vbscript (or similar) logon script to map drives: Mapping Network Drives - EduGeek.net Wiki
To hide drives, configure the settings in the aforementioned GPO with loopback policy processing: Using Group Policy Objects to hide specified drives
I've used this printer logon script to handle terminal services sessions.