You can not prevent dust/crap from slipping into the case.
Putting a screen protector on has no effect on being able to remove the case. I put my own screen protectors directly onto the ipad screen and have no idea what you're talking about with the otterbox becoming conjoined to the screen protector.
Putting a screen protector on has no effect on being able to remove the case. I put my own screen protectors directly onto the ipad screen and have no idea what you're talking about with the otterbox becoming conjoined to the screen protector.