There's no server hosting on your part, they carry the servers (like Vent and Team Speak)
The requirements for the program are probably lower than that of whatever browser you are presently using, I'll fire it up in a sec and tell you how much it raises my memory usage.
You create the spot in their servers. I leave my firewall on specific Permission based. (It is annoying to have to have it ask permission every single time.. I'll fix that to auto do it later) so even a fairly aggressive firewall and nat settings, you will still be able to make your own channels, and join others.
It's taking up a very small footprint right now. I'd say it's taking up less than 50 megs of ram. my processor isn't shifting any bit right now.
If you can play sto, you can easily run RC
The whole thing other than your client is cloud based, hope that helps