Use shortcut keys to manage different versions of Word

I would suggest that you spend your study time learning shortcut keys in Word. They are consistent across all versions (from 97-2007) with very few exceptions. Since you are accustomed to using the keyboard with WP5.1, using shortcut keys in Word will not be that foreign.

Print out a list of shortcuts and work those into your routine. If you take that approach, for the majority of the time, it will not matter which version of Word you are using. And as an MT, the money is on the keyboard, so it's a double bonus.

Go to the Help files in either version (I'd probably go with Word 97) and type in keyword shortcut keys. Print out the list and really study them and work them into your routine.

As an aside, the spell check right-click menu does not have the copy/paste commands (as you discovered). You can't access the copy/paste commands when you right-click on a misspelled word because Word is going to give you options to correct the word first. You have a couple of options....on the spell check menu, you can choose Ignore and then right click again to get the routine text menu.
Your second option is to add the copy and paste commands to the spell check menu. This involves editing the right-click menu, which is not difficult, but it might be more than you want to take on at this point.

Good luck with your transition.