#1
I submitted 2 tabs - my first contributions to UG - 6 days ago and neither have yet been accepted or rejected. One has been voted to be approved but that's it. It's true neither song is very well known so if tabs are reactively moderated some voters may not have an interest/know the song etc, however, it was promised that they would be accepted or rejected in 48 hours or perhaps a little more. I suppose I'm asking how many votes are needed before a tab is accepted? Do the moderators skim the tabs that haven't had many votes?
#2
In my experience, lesser known songs, older songs or songs with existing versions take significantly longer to be approved. Whether you have upvotes or not doesn't seem to make a big difference, unless a tab moderator has voted on it.
This year, the longest time I've waited has been around 6 weeks (video game tab) and the shortest was on the same day within 2 hours (brand new song from well known band).
This has happened several times to me and I see the same trend in the approval queue.

If you're waiting for an absurd amount of time, a moderator may help you out in the "UG Contribution" forum. 1-2 weeks seems to be somewhat normal these days even though it (inaccurately) says 48 hours when you submit. The amount of submissions has probably increased a lot the last couple of years.