Bone dont rotate corectly

Hi, it is my first work in blender. I am making an human that can be easilly edited to make different character in animation/game. The modeling is over and now i am doing the bone. The complete body work, but arm do not rotate corectly.

When i do a rotate 90, the bone rotate but the arm only move at 45 degree. This cause bug deformation. It is the same for hand. The rest of the body work perfectly. I made 2 screenshot for show my problem
I removed double selecter bone and i dont see any glitch anymore. I really dont know i did wrong…

I have few other questions that:
Engine like ogre3d dont suport blender subsurf, is it possible to do it manually (subdividing verticle with deformation that subsurf do to keep poly round)? If yes, is it possible to keep original bone architecture?

What is the easiest wat to add texture to a complex form like human?

Is it possible to keep the bone architecture after adding cloth on the model ou i need to reconfigure bone everytime?

Is it possible to dete and merge bone?

When the mesh moves slower than a bone it is almost always because the verts are assigned to two or more bones.

In weight-paint mode, shift-LMB on a slow-moving part and you’ll see a list of bones that vert is assigned to. When you find the problem bone, go into your vertex groups and “Remove” the verts in this region from the bad vertex group.