germinating/transplanting germinated seeds

so i've got five seeds in a wet paper towel between two plates sitting on top of one of my fluorescents so it's warm underneath. after about 36 hours, i've noticed that the taproots have popped out of four of them - maybe about an eighth of an inch.

i used this same method to germinate five different seeds a couple of days ago and four out of five germinated within forty-eight hours. one taproot was approx. a half inch long and the other three were approx. an eighth to a quarter of an inch long. i planted these seeds root down no more than a quarter of an inch in my medium (coco coir/ perlite mix). then i stuck them underneath my fluorescent fixture about four or five inches from the light. i watered with a small amount of nutrients.

within a day, the seed with the taproot that was approx. a half inch long had sprouted and new leaf growth has already formed since. this plant looks healthy and looks like it will survive. one of the seeds sprouted what looked a healthy sprout but it ended up turning brownish and curling over. while i still have it underneath the light, i do not see it surviving. the other two seeds never sprouted after 2-3 days and i saw that mold had formed on both of them when i removed them from the medum.

so my question is, with these new germinated seeds, how should i treat them differently than before? should i let the taproots get longer? should i not be using nutes on the seedlings so soon? should the light be closer/farther away? is my humidity too high (sits about 40% in my room)? is my temperature incorrect (sitting at 75F)? is it just a fluke? these are the last of my seed bank seeds and i really want to do them right. any advice would be much appreciated.

thanks,
sulk