Argofan,

I would cut them into posts and let them season, if you have a way to keep the posts dry. Of course they won't be completely dry when you go to cut the joinery (far from it), but you will have some indication of which way they are going to bow, and on which sides the checks are going to appear. I am not a big believer in end seal for timbers. Makes sense for boards, but I could not tell a difference on my timbers. (I end sealed half of them and then decided it wasn't really helping - maybe I should have end sealed them as logs instead of waiting to seal them as they came off the saw mill).