yes you will need to add the nutrients to the water when you feed i feed twice a week once with nutrients and once with plain water but both feeds are ph'd to 6.5
You should be ok with a 400w hps all the way through in that sized tent, i have seen people use up to a 1000w but thats overkill if you are just starting up.
If i was you i would get a soil one too, i got my one from ebay for £4/$6. i dont use it much just to check the soil ph before i start, but before i had one i ran into a lot of soil ph issues and nutrient lockout problems that cost me a few plants, so i wouldnt give my one up, in fact i am going to get a better one soon
You should be ok with a 400w hps all the way through in that sized tent, i have seen people use up to a 1000w but thats overkill if you are just starting up.
If i was you i would get a soil one too, i got my one from ebay for £4/$6. i dont use it much just to check the soil ph before i start, but before i had one i ran into a lot of soil ph issues and nutrient lockout problems that cost me a few plants, so i wouldnt give my one up, in fact i am going to get a better one soon