150w .. but a bit inefficeint, so for autoflowers you could probably do 2x3 space at the most. with photoperiods that will require a 12/12 cycle you need more power over that time and therefore it'll cover about 2/3rds of the space compared to 18/6.. maybe 2x2.
the lights will grow weed just fine. you pay for efficacy, which means you can use less watts, and often means greater longevity for your light.
the best option will be the lm301 diodes, h or b is no difference, and run at 0,25 watts per diode. if run hotter, you lose efficacy and longevity. if run as samsung tests them for the spec sheet, then they will last 50,000+ hours before it dims to 90% of original intensity (longevity curve in spec sheet on samson,com) otherwise it will absolutely be reduced in longevity, create more heat and cost more in electricy, ceteris paribus