Welcome to the forum!
MatrixIII answered a lot of questions already (thanks), here is my reply:
1) A server is only necessary for a machine actually running the jobs/tasks. You can access this server with as much clients as you want. Each client can configure the jobs/tasks on the server. A client can access multiple servers, so you can configure multiple servers within one client. If you want several servers doing different jobs, than you need to install more server applications.
2) The setup won't allow you to do this. It's server+client or client only.
4) I think it does
5) You can even run it on a standard desktop machine, but the more you want from VC, the more resource it needs.
6) There is a quiet installation, but it is not up to date, so you have to manually install the server applications.
7) You can connect to all the servers in one client, so you can change the settings for all the servers in one client. If you have some .NET knowledge, you could also use the API to make server changes.
8) You can connect to all the servers in one client.
Uses Visualcron since 2006.