Rep Tempo and Breathing

I know how to breath when my rep tempo is 1-0-1, but what if the rep tempo is different (for example 3-1-2)?
Should I inhale slower during eccentric portion and exhale faster during the concentric? Should I hold the breath during the pause? Should I breath with my mouth or my nose? What is the best rep tempo for building muscles?

Thanks for any tips or links (and sorry for my english) :slight_smile: