While the neuter will help some, the main problem lies in the previous owner. Too often, rabbits are left alone in a corner of a room after the "honeymoon phase" wears off, making the rabbit revert to a somewhat wild state. Sit close to your rabbit, whether he's in the cage or not. Feed occasional treats by hand so he knows you mean no harm. It WILL take time. Talk to him, sing to him, read to him, whatever interaction you can. My bun is a 5 year old male, and is not neutered. He was not too used to being out of his cage and handled when I forst got him in November. Now he can't get enough. Don't give up, and don't be scared..... rabbits can pick up on that.
As for getting him back in his cage, I use Craisins. I shake the bag, and let him smell what I am offering. Then I hold a Craisin in his cage until he hops in. Feed him, and close the cage. Start by feeding him a few outside of his cage so he knows the smell and taste, then begin to use it as a bribe.