Hi, you can just join VH & have a free domain & add your
www.kie.ac.rw at a later date if you wish (Free of any charges)
But its usually better to have the main domain in the public_html area (Main part of site) for getting reports on your website activity via your control panel. I dont think this is so comprehensive with an add on domain, (if at all).
As for server details! VH has many servers & this is allocated at time of joining VH with a new account.