To see what's been most recently changed, download the spreadsheet and sort by the "LAST EDIT" column in descending order.  The most recent changes will be at the top.

As a note, the cells are filled with current date and time by typing

Control Semicolon 

Spacebar

Control Shift Colon

Enter

To change the text in multiple cells (they can even be scattered around the spreadsheet),

•  select the cells with CTRL-click 
•  type in the content
•   press CTRL-ENTER to put the text in all the cells. 

Enjoy,

Chris Lent