You will find that I am not very happy with the whole GD&T implementation in drawings.
Datums tags in particular have been the bane of my detailing experience in all of Creo.
One tip I can give you; do not use the primary planes as your tagged datum planes. Create new ones from surfaces whenever possible (it hides the underlying plane that is generated). Creo doesn't play nice with visibility in your model otherwise. I have put in several support cases with this and they come back "worked as expected'.
Also be careful moving datum tags ( the square unified version) around on your drawings. I am at release code M040 and it still causes hard crashes when you start moving these around on the drawing. Save often!
I made a datum tag symbol to get around this: Datum Tag problem
This one is for default text height. It may need to be adjusted for other standard text heights to keep the text centered (another infinite wisdom oversight).
As for hide/unhide in drawings... it is erase or delete. Erase means they are reserved in that view or drawing, and delete means they can be echoed on again in a different view. Just remember that you can only use a driving dimension once. If you use some of these features in notes using their "handle (d1 toln)", they -should- remove themselves from the view as well. All very confusing and the regen updates are -not- realtime; everytime.