Help! What's on my tomato plants?

I started my tomatoes from seed for the first time this year. Things went well and they are currently outside, some planted and others waiting to be planted. I'm in southeast Virginia, USA.

Plant 1- looks healthy be green but has some tiny bugs on the underside of the leaves. What could they be?

plant 2- no sign of bugs or disease but doesnt look super happy. 

plant 3- needs to be transplanted, has light brownish spots

Plant 4- tall and gangly with not many leaves and not a healthy green color. Browning along leaf edges

. 

Thanks!!