I don't like to cut off any of the fan leaves until they're 40-50% dead. I believe as long as there's some healthy surface on the leaf it will help, particularly at this stage, they need all the green surface area they can get. As the leaf begins to die off, usually beginning at the tips, I'll use my little scissors and trim it back to the green.
Watch your injured leaves though, that's a weak spot where bugs like to start first. (And when they get a little bigger, I will trim back or cut off any leaves that are touching my bucket/rim- bugs will use these points to get on your plant) Bugs are an almost unavoidable evil, but anything you can do to keep them from getting in and taking hold will help you , I can't stress that enough!
I use a 10x loupe to look at the teeny emerging shoots for burn on the tips. They're pretty cheap on ebay. I like the 420Scope, it's worth the money, and you'll need a good magnifier to watch for bugs and check your ripeness at harvest time, if you don't already have one of course.
Thumbs up on the MH light for veg and HPS for flower! Once I figured out that in the early part of the year, the sun's path of travel is still in the south, thus away and less intense. As days get longer the light intensifies as the suns path of travel moves north (NE), and the sun is directly above and intense as it's going to get.
So now, I just apply that to my growing cycle, and adjust my light source accordingly. Piece o' cake.
A little 40 or 60 watt cfl's all I use on my clones until they start showing some new green, then when I put them under my MH, I start out about 3' or so away. I let her catch up and get her feet under her and get a little root action goin', and we're off to the race!