At first glance we need more memory first and foremost, its using the full 1 gig of ram almost all the time. So I'll get more ram first, then we'll see if we actually need to go private hosting or if we can manage with the home connection a bit longer and save up for the future.
The processor usage varied a lot, but never went above 40% in the 2 minutes that I watched it last night, so I think we're fine in that department. The network usage on the server computer also fluctuated lots but didn't go above 70%.
As for the bandwidth usage I was not able to check. Apparently I need some sort of code number that my provider gave me eons ago and that I never used. This number is different from my login. It's possible to retrieve it on their website and they send it to you via your email with the provider, which I never used >.< so I'll try to call them soon I guess.