You can use MH for veg, only downfall to MH is they use more energy then flourescent lights and they cause plants stretch up to the light more with longer internodes. If it were me I would use a T5 flourescent light for veg then switch to HPS for flowering
Yes. A even better place is walmart if you can find them. I spent 30 bucks on a t8 twin floro from lowes, and 12 at walmart for almost the exact same thing.. Also use a cool and warm bulb. Enjoy your veg time.