DSL speed is slow tell me its reason.

Hi dear,
I have a 1MB internet connection and it is being shared by 4 persons. The modem is in my friend's house and I am connecting via wired connection. I just want to know if it's possible to do the following:
1. Check who is online among the 4 users.
2. Disconnect other user's connection when I am downloading something due to the download speed becomes very slow.
3. Access other user's computer remotely.
