Hello CB Yes a 600 watt MH should do very well for vegitive growth
Also if required to a MH does produce enough red light to induce flowering, although it is not as good as an HPS for that job.

I would say that 20c is enough for growing in, mine are growing a lot colder than that at the moment, it does however cause the plants metobolism to slow down if it's too cold.


Good luck .................. love mand xxx