I think I would hold off on the lunging for a bit (a break so to speak) and work on ground manners. Starting with tieing, a horse that doesn't stand tied is annoying among other things. How I would teach him to stand tied is to use the inner tube technique. - You need a very strong and well anchored post or piece of fence (something along those lines). Then you need an inner tube (strong, thick circular inner tube not a tiny bicycle one...lol). Take the inner tube and have it across the chosen tieing post (making sure it will never slide down and he gets tangled in it) so you have each hand on either side of the big circular inner tube (kinda like a big 'U' and the post is in the middle). You will tie your horse on the ends of the inner tube you held on to. (I hope that makes sense, it's hard to describe 3D circular stuff with words alone). Now when he pulls back the inner tube will give a little so that he won't strain himself or anything, and still give resistance. Thus teaching him to give to the pressure.