You are probably in for a real challenge to grow ginseng in TX.
It does not naturally grow there per maps showing the range of wild american ginseng.
North East Texas, and at the very lower end of a direct North facing hillside (700' tall) would probably be your best bet.
If you can find a place where there is a rock bluff that faces near due north or a little north east, then at the bottom of that bluff would be a good place to try it.
On your seedlings dropping like that. Sounds bad.
I would suspect a fungus issue of some kind.
You might try (organic solution) treating your potting soil with Actinovate before you start your seedlings.
I have never tried starting seng in pots indoors though... could be something else going on with that - for example you could be giving them too much light, or something else could be wrong.
Good Luck !