1. Root -use z4Root from the market or use this method if you are interested in the nuts and bolts of the operation:
How to root the Droid 2 - xda-developers
2. Purchase Droid 2 bootstrapper from Market and install it.
3. Download and install Titaniaum Backup from the market.
4. Use Droid 2 bootstrapper to make a backup of your still "Stock" system.
5. Use Titanium to backup all your apps, even bloat, then Uninstall your bloat apps. If you accidentally delete an app you need, it is easy to reinstall one app from Titanium. You may find that you need a bloat app to make another app work, so you can just reinstall it.
Do anything you want to your phone.
When update comes out use Droid 2 bootstrapper to restore your stock setup. You will not need to unroot. Update your phone. Then repeat these steps for the Updated system. I keep the original for a while just in case I do not like the update.
(If z4Rpoot makes a backup you may not need to follow this, however, I would just in case.)