For mouse wheel binds you need to set client (or d2se, whatever you use to run the game) to windows xp sp3 compatibility iirc.
By right button, It means activating skill with RMB. You use 2 skills in d2 at same time, left and right button.
If you have stance on right skill, and fortress on left, you cant shift+left click fortress because bear stance locks it, so you have to change right skill to fortress -> cast fortress -> switch back to bear stance.
You are not supposed to change what left and right mouse button do in the game, their default functionality is fine (activating left and right skill that are currently displayed on the screen).