Selection:
Switch to object/edit mode: tab (switch between active mode and edit mode)
Select multiple objects: ctrl+right click (shift + right click)
Modeling:
Select ring: ctrl+alt+right click (select edge ring, in edge select mode. Selects a face loop in other select modes)
Recalculate normals: ctrl+shift+N (ctrl+N for outside (usually), ctrl+shift+N for inside (sometimes))
Select connected: L (under mouse cursor. ctrl+L to those already selected)