If you aren't used to using the 'F3' key to toggle the snap settings on and off, then try this:
anytime, even during a command, hold the 'shift' or the 'CTRL' key down and at the same time 'right click' the mouse. On the menu that comes up you can either pick a snap, or go to the settings at the bottom.
When selecting objects to erase, if an object is selected that was not meant to be selected, then this is what you are to do:
Press and hold the 'SHIFT' key, and de-select the object that was not supposed to be selected in the first place, then you may carry on with the erase command.
It is a unique trick to enter text in a circular path. To do so, type TEXT and then Enter. Type just a single character, such as 'r' as the text.
Next use the Array command to create a polar array of the text character. Select the text and give the exact number for total number of items prompt, then press OK.
You will get 'r' in a circular path. You can then edit each text character and replace 'r' with the character you need.
Note: Be sure in the polar array at the "total no of items" prompt to enter the exact number of text that you need.
Go to your autocad support file (where 'c' is your drive) c:\program files\autocad 2002\support\ and look for the 'acad.pgp' file. Double click on this, you will find all the typed shortcut commands.
Also you'll note that in the command line when being prompted all the words in brackets (aside from the ones inside > which are the default commands) have either the first, or the first and second letter as a capital, these are the only letters AutoCad requires to process the command.