First Grow, need help with seedlings. w/pics

Hey, This is my first grow and i just picked up a grow tent with a 250 w metal halide and hps bulb.....i started them under a 24 watt flourescent and just recently transferred them under the 250 w metal halide in the tent. I have noticed that the first set of leaves on 2 rocklocks have started to fold but the newer leaves that are coming in look fine. Also the 2 rocklocks in the back left seem to of had a little stress as the light cycle changed when they first sprouted because they were brought from a window to being under flourescents over night but the newer leaves on them seem to be growing fine and one of the embrio leaves never grew since day one it was just yellow and shriveled up. I have had the rest of these plants going on 18/6 since day one and just recently the stem on one of my lemon skunks has started to bend and become weak so i moved it outside to hope it would help toughen the stems up a bit and as i am trying to get it use to growing outside. I have been watering every other day or when they start to dry out. I was just wondering what could be causing the stem to fall over and bend and do the rest of my other seedlings look fine.

What is the temp?
You may have to stake them up.
Do you have a fan blowing?
Not all strains can take heat the same.

not sure on temperature i am going to pick up thermometer tommrow but there is not much heat as I have the fan blowing and the light isnt too strong.....I just staked the lemon skunk with the weak stem and im hoping it will toughen up with the fan blowing on it.

They look healthy for now, guess you will find out in the next two weeks what is going on with them, but for right now they look pretty healthy.

I am planning on moving 2 of these plants outdoors but i was wondering if any harm will be caused because the light cycle will be changed. I have had the timer on for 18/6 turning off at 10 p.m and coming back on at 4 a.m. Will increasing the darkness overnight outdoors have any serious affect on the plants?