Hi GrandKw,
1.) Yes, users can signup for a server, and it will be deployed. Typical deployments take about 30 seconds. Users then get an activation email.
2.) Yes, you can attach as many slaves as you like to the master.
3.) Yes, we integrate in with both WHMCS & Blesta.
More information on the blesta module can be found at https://docs.blesta.com/display/user/SolusVM. Info on the WHMCS is at http://docs.whmcs.com/SolusVM