Thanks to everyone that's tried to help.  

I have read what I can find about the differences between VATSIM and real life, so I'm fairly familiar with most of those differences, including VATSIM procedures used when a controller isn't online (see my first post).

I asked my second question because the tower wouldn't normally have control over the entire class B, so as a VFR aircraft entering the class B it wasn't obvious to me either from real-life or VATSIM's procedures that I should contact the tower for permission to enter, when center and approach were both offline at the time.  Of course, that left the problem of when to contact the tower at all, so it makes sense that the tower should control the entire class B on VATSIM under these conditions, but I was wondering if it was normal procedure or not, because that would be contrary to the top-down heirarchy VATSIM usually uses.

Steve

Welcome to VATSIM!

Yes, you've figured out the top-down methodology perfectly.  You can always ask up, never down.  Yes to all of your questions.

Thanks Don.  

I guess that means that en-route controllers can get pretty busy, if they are the only ones online and have to act as clearance delivery, ground and tower positions for all the unstaffed airports in their area.