Try taking a rope and make a u shape at the bottom of his leg in front and pull up this will give you more leverage to pick up with. Just don't wrap it around his leg in case he pulls away or spooks. Also when he try's to bite just put your elbow up and block him. But don't look at him while you do it or it will become a fear thing for him. But make it count don't just give a little fly tap, almost make it seem like he ran into your elbow. This all is kind of hard to explain but I hope it makes sense. We have used both of these methods with horses at our barn and they responded very well. Remember to reward when he does the right thing or this will all be for nothing. Also when you are working on picking up his feet if at all possible try not to tie him up so he doesn't feel trapped. We use blocker tie rings and they are absolutely amazing for training and horses that pull back and rear.
tie his head up so he cannot bite you or put a muzzle on him. pinch the chestnut with one hand and be ready to grab the leg with the other hand when he picks it up. if he doesn't respond, start twisting the chestnut. eventually he'll hold his leg up for you when you start running your hand down along his leg.