I have tried a few different transactions, I find that I only get email when low limit reached. If I set it say 10 then when I hit 10 left I get email. If I reduce it further I get email telling me the new level.
To use it for full stock notification You would need to set your low limit at least as high as your full stock level.
Uncheck the Show quantity in stock check box (under appearances) hope this helps
The 1st pic is admin with check boxes cleared, 2nd pic is customer side which doesnt show the value because of that
do the check box 1st and see the results
3rd picture is before I edited anything out. (2nd pic where it says condition I put that in as I was going to put all the fields in admin ready for google base feeds-might leave that in customer side yet)
final picture shows the email. just from a dummy site I use to test tells you stock left