2 questions one involving a veg. and one a lighting q

first question...could u let a plant grow on veg growth for like a year and could i grow like up to a tree or would it stop after 20 or so feet?

second is.. with hps lights do u need a balast for all lights even if its a 70 watter ..u couldnt just use a standard clamp light fixture?

You can veg for a year, but there's no telling how tall it will get. Yes, you need a ballast for any HID light such as MH or HPS.

My mother's are A year and A half and still vegging! And the HID does need the app. ballast!