To slow his trot, try slowing your posting. Also to get him into a nice frame you need a lot of legs and a lot of hands. What you need to do is push your horse into the bit by squeezing with your legs and hold him back with your hands. It's easier to do while you are doing a sitting trot. Also do circles practice making the circles bigger then smaller, using your legs.
As for jumping, I'm not too sure why he is stopping, but it could be he cannot see his spot, for that I would recommend trotting ground poles, then build up to small cross rails. I know cross rails are harder for horses to see the distance on then verticals. Trotting ground poles will really help him know where to place his feet. While you are jumping always keep your leg on to encourage him to jump. I wouldn't use spurs yet unless he is stopping just to be a brat. But I'm going to assume he stops because he is unsure.
I would also quit with the free jumping, he needs to get used to jumping with a rider on him, so he can learn to trust you and listen to you and not jump how ever he feels like it.