My douts in internet

Hello,

i have 3 user accounts in my pc and one is admin account and other 2 are limited account.

My doubts:

1. in limited user account it say u cant wirte down any cds.

2. (INTERNET) i am using airtel connection and i have unlimited download option from night 9pm to morning 8am. how to set the limited user acount internet connection in such a way that they can use internet between 9pm to 8am.

3. how to restrict site that contain virus .

4. I want to view these sites only (yahoo, gmail, hotmail, coolmail, google, aol.) by I.E and restrict other sites.

please advice me on these issues.......:)