Pics are really helpful but I think I have the answer to question 1. Your seedlings probably stretched towards the light because they weren't getting enough. So they reach making them tall with a thin stem and the poor thing just fell over. Prop it up by tieing it to a stick of some sort and move them up towards the light, they should only be a few inches away.

Question 2
I don't know much about nutes, but when you do start (2 weeks after sprouting roots should be good) Start with 1/4 strenght for a feed, then 1/2, then 3/4. Alternate between feed water and pH water till you learn what your plants can take. Also I hope you have a pH tester, test your feed and water (I use 6-6.5pH) and also test the run off 25252525222555555522252222222222222225252252522522 5222252255552525252525252high every body22222222222222222222222222222( my husband saying hi andtrying to lure me away from the comp)

Anyways if your run off's pH is way off you may have salt built up and it's time to flush, but alternating the feed and water should help avoid it.