Og kush auto

That 300W LED is more than enough for one plant as long as it's TRUE power draw is 300W. I don't know what the wavelengths are on your floodlight, but it might not even have usable light for photosynthesis. You may risk burning them without benefit.

I also run a 300w LED. For me it was: Seedling: 30" Veg: 24" Preflower: 22" Flower: 18" You'll have to see how they respond, but this should give you some guidelines.

It all depends on your set up and your preference. 18/6 is commonly used for auto throughout the grow. I see you are growing in soil, so I would water them 1-2 times a week. Make sure your pot is almost dried out before watering. Less is more for soil. For details check this out: https://www.growweedeasy.com/how-often-water-marijuana