First Pic: Looks pretty near perfect as far as your position goes. All I can see is that you are jumping ahead ( crotch over pommel rather than over the seat). Release is great, upper body posture is good, leg is solid, no complaints!
Second pic: You really lost your leg here, which has caused you to lay on his/her neck. You've dropped your elbows- therefore defeating the purpose of a crest release. But you still have your heel down and a nice flat back. Not bad.
Third pic: Thumbs-up! Open your shoulders and keep your hands a little lower. Good other than that.
Fourth pic: Not too much of a conformation critique but he looks decently put together. Looks to be lacking muscle in the hind quarters and shoulder area. An upright shoulder from what I can see, which will limit the movement of his fore-legs. A flatter croup is good for endurance but not as much speed. On the back, his cannon bones look a little long but hey, what do I know!?
Fifth pic: Hands are a little low but looks fine otherwise.