The 1000w easily will blast 3x5 feet with tons of light. They grow huge plants in 5x5 feet area. one big LST plant that pulls a pound and over from one light. Check out hygro-hybrid on Youtube. He does it ever grow, but in DWC.
I know a local grower that pulls a pound off each plant in soil or soiless, can't remember, with 1000w per plant. He uses general hydroponics, but recently switched to general organics line. He feeds the plants every three days, nutes, then water, back and forth.
He runs his on automatic timers, but would prefer if he could be there enough, to water once the top soil was dry. Be sure to ariate your soil well. He mixes his with coco and some perlite.
I've seen added bark for plants do great things.
The 1000W will put off WAY more heat than what you got. Be sure to get a good cool hood with at least a 6in fan ducting that you can pull out of the room and into the attic or somewhere. Keep in mind that if you just throw hot air out a window in winter time, cops can see that on their infared cameras. If the heat comes out a window in summer, no big deal, so long as it matches air conditioning. Just things to keep in mind, even if you are legally allowed to grow in your house, apartment, even if the lanlord doesn't care.
Plants are looking great.