I had joint fusion of my ankle following a fracture of tibia and fibia. I've been cleared to walk again, but I'm in pain w/ every step; same as b4 surgery. Is this normal?

No. There could be some pain after coming out of immobilization. Depending on how long you are following surgery will depend on how much discomfort you have. The pain however should be less than before surgery. You should have a repeat x-ray and be checked.
Depends. If the x-ray shows that he fusion is well healed then it is ok to begin walking. If there is a question of a delayed fusion, then there is no benefit to walking on it.
No. Assuming it has been some time since surgery, a successful fusion will lead to stiffness but should be pain free. I would worry about a non-union, infection, or other injury that has not yet been treated. You should make sure your doctor knows this.