[Digital Jedi]

Unfortunately, no, the licence of vB wouldn't allow for a sandbox environment, other than the demo.

You're not stuck with the default style, as you may notice from the demo, you customize your forum colors from the Admin CP controls. Or you can just pick up one of the free skins here. Or you can buy a professional skin. I've seen them range from $30 to $50. Or you could hire a coder here to make you a custom one in the Paid Requests section. Lot of options there, really.

Usergroup permissions are feature rich, sometimes to a fault in that a lot of users don't realize what they can do with them. Permissions themselves go pretty deep and can even be on a user by user basis. I don't see you having a problem there.

Events are controlled via the Calendar, and even as far back as vB3 they've had Usergroup based permissions. Those permissions are not quite as in depth as the forum permissions, but they still would do what you've mentioned here. Base creation, deletion, editing and viewing on a permission basis. Also, you can create events on a reoccurring basis based on X number of days if you need something other than the preset Daily, Weekly, Monthly, Yearly and Every weekday settings.

The only thing you would probably need a modification for is if you wanted the Calendar events posted in a forum automatically. I don't recall if vB4 does this. I know I have a modification installed on vB3 that does this automatically, so you'd probably need to search for Event Forums in the search bar. Also, I'm not sure what you mean by RSVP, but that would probably need a mod, too.

But other than that, I don't see you asking for anything that vB doesn't really do out of the box. Customizing colors doesn't really require any coding, just patience (especially in vB4) and time. Plus this community is pretty helpful when it comes to helping you find what you need. I'm not saying we answer or even know every question, but we have a pretty good ratio of helping out when we can.