Ok I've just read through from the beginning. Your drooping/slight yellowing is, I think, the nutes from the soil. I grow in coco myself so I can't say what's best for you but I'd make sure to use something more appropriate when you transplant. You could put some more soil around the top to prop up the stretchy or floppy stems for now if that's still an issue, that'll also give you more surface area under the soil to develop roots. The more root growth you get, the more top growth there can be. Wait until you have a decent rootball before you transplant into their final pots, if that's how you're doing it, but don't let them become rootbound. Also, the better quality light they have, the more water/nutrients they can process so I'd probably listen to everyone who recommended changing the spectrum of your bulbs for this stage in their development.
That's my tuppence worth. You're obviously willing to learn so keep asking for feedback and you'll do fine. Good luck with it man