1) I think this is a common issue for multiboxers, waller jailer, partly frozen can make u caracters desync. What I do is to have seperate keybinds for my caracters like
screen 1 - a and share space
Screen 2 - w and share space
screen 3 - e and share space
screen 4 - r and share space
but more experience will make easier for you to adjust to the affixes and resync on corners and smaller objects, I dont see this as a huge issue for me atleast not anymore.
2) I'm not sure what the rules are on this website and therefor I can't tell you which programs, but there is programs out there that tells you when a legendary drop on your other screen, you can set it the rareity to what you like, but i wont pick up for you.