I've just downloaded DT Pro Public Beta, so now what do I do now? I don't want to move totally over to Pro right now if it's just the beta, but the readme file says that you can't run DT and DT Pro because services, etc, will get screwed up. Should I move fully to Pro? Also, in Applications, there's DevonThink and this program is named DevonThink Pro, so I just add the latter, do I just delete the former? this won't delete anything related to the database will it?
The public beta of DT Pro is free for a limited time of use, and you can try it out without risk to your current DT PE database.
Before downloading DT Pro, I would advise that you go to the Finder, and in the Applications folder select the DEVONthink application and tell the Finder to create a Zip archive of it. Then delete the application itself. Your original application will be available in the future by simply double-clicking it to open the archive.
Now install DT Pro 1.0 p1 and launch it. On first launch, it should find your existing DT database and make a copy of it in your Documents folder. Therefore, you will still have a viable DT PE database left in its current location.