Append or Link

File > Append or Link...

Link = XRef
Append = Merge

Temp file location

Windows Vista = Users\Username\AppData\Local\Temp
Mac OS X = Go to folder (Shift Cmd+G) and write /tmp


Inside temp folder you can find:

Quit file = Always made when you quit Blender
lastsavedname = Last saved file

Timeline range

Set timeline range = Go to frame you want to set as S(start) or E(end).

Rip UV vertex

Disable (rip vertex so shared vertex can be moved) = Shift+C
Shared location (default) = Alt+C

or from dropdown list