First Grow Ultra Lemon Haze issues and Questions

Hey Guys,
So this is a picture of my first grow,,,, The two bigger plants are 3.5 weeks old and the 4 smaller ones are 2.5 weeks old (from the day they sprouted). Personally I think they look decent but I'm sure there's room for improvement. I've got them in a secret jardin dr120t tent, under a 600W MH grow light, which is cooled effectivley by a 6'' fan/vent system. I have an oscillating fan providing air movement, and the temps range from about 68-73 degrees Fahrenheit, and I'm on an 18/6 light cycle. The four smaller plants are Auto Seeds Ultra Lemon Haze, the biggest one is BlimBurn AK Auto, and the 2nd Biggest one is G13 Diesel Auto. Ive got the Ultra Lemon Haze's in 2.5 gal pots and the other two in 5 gal pots, of organic potting soil/ pro-mix/ vermiculite mix. I use jack's all purpose 20-20-20 at 1/2 strength every 2 weeks, and plan on using the blossom booster 10-30-20 for flowering. One mistake I made was not realizing that Ultra Lemon Haze strains aren't really autos, so I don't know how to deal with that considering my other 2 plants are autos....

My questions are the following:
Is 68-70 degrees a good temp range?
What should I expect to yield with my current setup?
If i switch to a 12/12 light cycle to get the Ultra Lemon Haze's to flower, will this harm my other autos?
How close should my plants be to the grow light?

your temp range is okay but the sweet spot is 75 degrees.
depending on how long your vegging for or how tall your plants are you may get a half a pound or so. it also depends on the strain so there is no excact way of knowing what your going to yield.
you will be fine switching to 12/12.
if you have an hid light then the distance from the canopy should be 12 to 18 in. but if your using fluorescents or cfl's you can be super close to the light...2 in or so.

Thanks Buddy