#1
okay, so i have had my gretsch G5120 for about a year now and i have had saddle buzz for most of that time. it comes mostly from the saddle screw on the B string, but it sometimes comes from the highe E as well. it seems to be because the saddle screw (used to adjust intonation) is loose. i've done full setups with the screw properly tightened and whatnot, and it always seems to come loose within HOURS!!! it also appears that the B and high E saddles are backwards (how it shipped, dunno if its right)

this is starting to drive me mad, any ideas?
#2
that is how they ship. but there is no real right way to have them as long as you can intonate the guitar properly.

you would think the pressure of the string would hold it still but i've seen the same thing on les pauls.
#3
Try some clear nail polish on the intonation screw, or some pva glue, just something that will hold. Just dont get it on the saddle grove. Its probably just a cheap bridge so the screws dont fit properly causing them to vibrate when you play.

Alternatively buy a new TOM.