Emailing professors for PhD programs before applying?? Micro/immunology

[meghanx0919]

I am applying to various microbiology/immunology PhD programs for next fall. I know it is essential to email professors before applying but all of the programs I am applying to do lab rotations or are umbrella programs. Would I be annoying to still email professors to ask about their program, even know they don't have too much of a say on the applications. Or should I email the directors of each program first with general questions?

If you applied to programs that did rotations did you email professors BEFORE you submitted your application?? OR would it be more important to email professors if I get interviews?? 

Thanks!