ok with these types of questions i am assuming that you don't even have linux installed ...so here i go ..
1 - same as windows, click the restore/maximize button
2 - depends what your using i guess, but again same as windows file -> save
3 - open up a web browser
4 - well yes but its not called a start menu
5 - i assume you mean ALT-TAB (again like windows) or click it in the "taskbar" (also like windows)
6 - one mouse button for what? you use the mouse like you use a mouse for anything else ..
7 - same as, you guessed it, windows ... navigate to the menu its under and click it, or type something like xcalc or kcalc (there is many, not just one) in the terminal..
8 - as many as you want ... its a true multitasking environment, even at command line ;-)
9 - don't worry about them
10 - xmms plays music, its identical as winamp, also there is a winamp in development
11 - sure there are, many for that matter
12 - you can use openoffice or staroffice (equivalent to ms oFfice) .. openoffice is the free version of staroffice ... and you can even save in ms word format
13 - adduser <username> at command line, or use a graphical tool in KDE or GNOME (these are desktop environments)
14 - same as you won't open a file, again just like in windows ...