hey first things first sort out the text on your post or youll never get a response not many ppl will be bother to read
text when its typed like that
anyway back to business
from what you have wrote and told us, it sounds as if your doing everything ok , the seedling will disgard the seed casing naturally to release the first leaves (cotyledon) it will happen don't try pulling these off as you may damage of even kill the seedling.
after this point the first true leaves ill grow from the middle,
your temps and humidity are both fine
try to keep a slight breeze over the seedlings moving them slightly back and forth as this will help to strengthen the stems
make sure your light (600w) is kept inbetwween 1 1/2 ft to 2ft away for the first week they pop to avoid light burn,
after the first true leaves show i would reduce this to 1 1/2 no more than that away from the tops of the plant to avoid unnecessary stretching
if you follow this you show be fine
oh one more thing dont use any nutes till at least the end of week 2 start of week 3 and when you start with nute use only 1/4 strength and work your way up