I have encountered this most often with brace larges and walkway covers. I place down the piece using coordinates of course and then I load up the map again and the piece will be moved slightly. Just enough to not notice unless you select using coordinates and it will then snap into place. But it will just do the same thing the next time you forge or play the map. If anyone has a solution for this "O.M.A.P." (Object Movement After Placement, that's just what i'm calling it) then let me know. Thank you.
No, there is no way to avoid that. What you have to do is work with it. Place it and save so that it moves, then go back and with rotation snap OFF adjust it and its surrounding objects so that the edges line up as well as you can get it. so that it does not hugely impact grenades or bump players.
Unfortunately no. Big pieces are most affected by it - I've had issues with brace larges, coliseum walls, platform XXLs, and others.
Stevo wrote a guide on that, actually. It is similar to Ladnil's instruction, but not the same. Here it is.