When they are starting out, its very common to take 2-4 days between watering, depending on how much hydration your mixture holds. So the fact that you 'waited' 2 days for it to dry out, leads me to believe you've been over watering. Which as stated above, will cause drooping.

Roots: I wish I had my pictures of a rootbound plant. I've had quite a few that took up as much volume as the grow medium in the containers, so it would be equal parts roots and soil, basically, I would pull the plant out of the container by the stem, and the soil wouldn't move, none would fall off, and I'd have to pry the roots to get to the soil underneath The roots gathering on the bottom and then searching up or down is normal, they congregate where the moisture is, and then when they start getting dry, they go out in search of more. This is normal, and not bad.

As far as your pretty little girls go, you just switched soil, so give them a few days and let them use up the moisture you've got going now. Then maybe start them on a low dose of nitrogen, because thats all this looks like, is a touch of over watering, and a lack of nitrogen. (Btw, the over watering would be the reason you don't have enough air in your mix, but you can always stand to use more perlite)