Yes, I was confusing temporal memory with temporal pooling.
In your answer to #1, you are saying that there would be a union as far as all cells in a minicolumn being active, but not a union as far as two different patterns (of active-columns) being simultaneously active.
I think I understand why I had the belief that multiple patterns of active cells could be represented at the same time. If sequences had already been learned, and then learning was turned off, you could do the following: You would present the first terms in an ambiguous sequence (as few input-vectors), and then the temporal memory would be allowed to “imagine” what comes next, by converting predicted cells into active cells. That way you would have a union of active cells.
(I re-edited my first post to straighten out the terms pooler vs memory)