I posted on your site as well, but saying it again here: great job.
I don't have the time to do all of the exterior locations, but as soon as I saw the last room of the keep I decided to make a 3D version. Should make for a good climax for the group when I pull out the full 3D dungeon.
I've created the parts for the statue of Orcus, I need to assemble and paint them and I'll start casting the floor tiles next week.
Don't count out the basic Hirst molds, they're more valuable than you might realize. I went that route too thinking I wouldn't want the basic mold, but eventually I picked it up.
There are obviously a large number of sites you can hit to find out about terrain building (when I started there wasn't even such thing as the Web

),
www.terrainthralls.com is an excellent one.
If you haven't seen them yet Osprey puts out two excellent books on terrain building.
Good luck and great job.