Assume 100bb stacks for all these,

1) 2 folds, loose/passive CO limps, button folds, SB completes we check in the BB and flop middle pair on lets say a K 7 4 flop. SB checks, whats our line?

2) 18/10 open limps in MP, folds to us on the button with 6 7 . Raise/limp/fold? Does it all depend on how often he folds to cbets?

3) 2 folds, 42/35/4 CO who basically has no fold button raises pot, folds to us in the SB with K Q. Whats our move?

4) We hold AK in the BB, 20/12 UTG raises pot, folds to us. Call/fold/reraise?