How do I apply UV mapping to objects so that the textures appear correctly? The textures appear too big or too small. Is it possible to apply six different materials to each side of a cube? Is it possible to delete faces from objects? Is it possible to have selected object appear alone so that I can work on it without having other objects get in the way?

In WED, textures have property values which you can tweak to get the textures tiling to the size you want, select the texture you have on your block 'thru' the texture thumbnails and set their sizes accordingly.

Textures on a cube can only be achieved (AFAIK) by including all individual textures in the one file and setting each face to the part of the texture you want that face to have.

Its not possible to delete faces outright I dont think but you can reduce by welding or merging vertices directly (outdated now maybe).

Not really but a similar effect may be achieved by using the 'scope down/up' functions where an individual selection of a face from a block may be isolated and worked on.

You will find all answers addressed in the basic exercises found in the Mighty Manual.

If I want to texture a long wall, how do I tile the texture X times? I was able to give each surface of a cube using the surface tab of object properties. I think that 'scope down/up' functions work on groups of objects, not objects in 'root' on level tab.