Windows 2000 VPN Server Implementation Issue

[iria1004]

To All,

I have some issues for my company's VPN Server configuration.
Today my company hold a "work-at-home" plan.There are 14 users
working at home. But the situation is not good.

Now I have some issues to talk.

VPN server is our company's firewall/NAT server.

1. Does VPN Server authencitation need to go to DC to register?
2. I setup DC's gateway as VPN server,Am I right?
3. If I didn't setup DC's gateway as VPN server, Can I successfully
logon Domain?
4. My collegue's PC is behind "Hi-Building". I found he has a lot of
trouble to logon our company domain. why??

Please help me for these.

Thanks.:>