As of right now, the [tag:Windows-8.1] tag has 16 questions currently, and the tag summary reads:

 > Windows 8.1, code name "Blue", is an update to Windows 8, scheduled for release in late 2013.

Regarding the two questions posed above:

1. There is no such tag called [tag:windows-blue] at this time, and agreeing with what [@nhinkle][1] stated below, I don't think it's necessary unless people start using the tag (Windows 8.1 is the more official name).

2. As of yet, I am not sure if [tag:windows-8.1] *should* be made a synonym of [tag:windows-8], in the cases where issues do happen to be specific after upgrading.  For those particular questions however, *if* the two tags *were* made synonyms, I think it would be just as clear to tag the question with both [tag:windows-8] and [tag:service-pack] (again, like how there is no SP1-specific tag for [tag:windows-7]).


  [1]: http://meta.superuser.com/users/20088/nhinkle