You look to be on track pretty good. The MH will definitely facilitate vegative growth better than the HPS. As long as you take advance from others (presuming it's good advice) and use common sense, you'll be good. This has been my first AF / indoor grow too. It's been 5 years at least since I've grown anything. Used to grow photoperiods in a greenhouse, so I had to pretty much learn everything over while getting my room dialed in. So you can definitely make it happen.
What kind of nutes are you using? My NL's are pretty heavy feeders, last feed was at 920ppm, pretty heavy for autos. My skunk #1 autos didn't like to go over 600ppm. The NL's seem to be pretty big nitrogen hogs as well, I wouldn't feed yours anything for atleast another two weeks or so, then start slow and slowly build up, we'll be here to help you out along the way. There's nothing more fulfilling than taking that tiny seed and turning into a labor of love, I forgot how much I love cultivation, and i personally think you have to grow your own medicine in order to fully appreciate this awesome plant, instead of how other people see it, just as a drug, or something to get you high.