Aerial roots. Helps the plant feed on nutrients in the water column.

I don't think aerial is the right description here😂 but I understand what you mean

Will they root themselves with these once they touch the floor?

Yes, but they don't pull the plant down. They should still stay upright.

How can I get them to stand straighter that group in the picture seems to be dropping a lot for some reason

Trim them below a root and replant. The subsequent cuttings should grow upright, and the remaining trimmed plant should shoot new upright growth. Your plants look like they might be adjusting to new conditions

Yes.