1. Involving all those other nodes is the obsolete convoluted way because the plain old mia_material does not have a bump slot so yes just plug the map into the standard bump slot.

2. You don't have to use MR textures with MR shaders, the Maya textures work just fine. With the mentalrayTexture, there are usually other connections and nodes involved and all that might not even be necessary if you wanted to say...put a concrete texture on a warehouse floor.

3. I can't think of any, a lot of what I know comes from spots around the net, the help files and a ton of experimenting.