question about 2000 advanced server

[moonnightingale]

.First of all i want to explain you my whole setup in detail.
In our setup we are using two computers.One for upload having windows XP and other is server having windows 2000 advanced server.for reception we use a dish antenna which directly gets data from satellite and feed this to receiver which is Linux based.From receiver it is fed into server and then to user.Server is also connected to gateway computer(Cmputer having XP).In my server computer 16 modems are instaleld. USers connect to internet through their own modems and maximum 16 persons can use internet at one time.(( I might be wrong in terms but i just want to give you rough idea about my setup)).My queries are as follow.
1.I want to disable the option of multiple login.I mean some time two different persons are sitting with single ID and some times more than two.I want that at one time single ID should be accepted by server.
2.Secondly i want to keep track of all the websites visted by my users by mainting the record in a log file and this file will display all the sites visted by users respectively.For example if Mr.A visted www.yahoo.com and MR.B visted www.msn .com it will show the same way.
3. Lastly i want that if a particular user has used internet for a specific time assume 1 hour it should disconnet from internet automatically.
Ok i am good in C language.Tell me if i make program can i link it up with windows.Kindly help me i will wait for u people. bye
moon