It indeed seems like it is a waste of space to repeat "Questions on...", and as far as I understand, the SE engine should truncate these when the excerpts are displayed in e.g. the mouseover box. On the other hand I could not come up with any good English phrase that can be used to start a sentence and does not render the excerpt to something that is barely better than a list of keywords.
Anyway, I think we should remove the redundant words, and if that is the general consensus I will slowly scan through the most used tags to do it.
Bearing in mind that the displayed excerpt is truncated and most of the time only the first ~20 words are visible, I would suggest providing only one sentence with the most barebone essentials that help delineate the usage of the tag and distinguish it from other tags.