Hiya.

Do a quick "look through" of the tutorials for WED, MED, etc. That should give you a basic grasp of how WED works and how to incorporate static meshes into your 'world'.
I think the Extra edition does let you use the "templates"; this is probably what you are looking for if you want a "click-together" type world where you just select a pre-made action for a particular entity (example: Player control, ammo and health pick ups, simple doors and triggers, etc.). Look into them to see what they can do.

My first suggestion would be to take a VERY close look at your terrain. That can be one of the biggest slow-downs of compiling a level...all it takes is a few badly intersected polygons or some such and you're looking at hours and hours and hours to compile.

If you can give us more info, I'm sure the bright folks here can pin point your slowdowns and errors.