Hi John, Friday's thru Sundays are very well staffed. Use Spy, vattastic.com, or vatview.com, qutescoop, all tools tell you where we are hiding, or available . Since the holidays are coming, you can expect slightly higher staffing levels in the evening times and other times during winter holidays.
I would say, get FSX up and running first, then get familiar with your acft, then the VATSIM stuff...trying to learn all 3 at the same time may be a little bit overwhelming, in the sense that should anything go wrong, you won't be able to tell which one is causing trouble. FSX, in itself, is a beast, a messed up beast.
If the dll you were talking about was UIAutomationCore.dll, then good, if not, look it up, to save yourself the pain of crashing FSX, not the acft, but the software.