Distribution Server Questions

Hi,

I have questions on DC Distribution Server (DS):

Where is the directory/location of software in Distribution Server? Is the location contains software copied from Desktop Central server?
Is the Distribution Server works only on Windows Platform?
In our LAN we have different VLANs, if my DS is in server VLAN (192.168.10.1) and my clients are in separate VLAN (192.168.1.x), will the clients still communicate to DC which is in different VLAN?
After I Install Software, I noticed that it took about 30 minutes for a Skype to install from DC to client PC in remote office (with DS), how would I know that the client is communicating to local DS and not from the DC in HQ?