I have never done or really seen saddle seat, no help there.
I can help you out with the top picture, I would say sit straighter if at all possible, loosen your reins (relax its riding not murder), put your heels down.
Tip on the heels, stand on stairs & hand your heels for about 25 mins a day, yes it hurts but it works. Or what my trainer would do was make me sit a Two point & then go have a long conversation with someone on the phone for say an hour or so.
Hope it all helps!
By the way, I am horse napping Razz! He is so pretty... its the shine. How do you get him so shinny??