Joints for me, plus when you run out you have those nifty lil roaches to smoke on till your new bag comes lol. I'll smoke out of anything though, as long as im smokin I'm happy. lol
Imo I usually water untill i get a bit of runoff, I like to keep my soil well flushed so i have no salt buildup. I water when the soil is dry about 2" down and feels light.
As for the fox farm nutes, I have no experiance with them but I believe I've read to start with 1/4 or 1/2 strength.
That i couldnt tell you, i dont own either of the 2 descrided, but i plan on ordering a 1000w dimmable off of ebay. so i guess it just depends on what you want to do.
By options i mean like lets say you have a heat wave were you live and your room gets too hot you could dim it down, or you could dim it down to start plants and increase it as they get bigger. I think it would prolly be better on the bulb to be dimmed down so it might last longer. jmo