How do you handle a cavalry's unit follow-up pursuit 2 movement and attack when dealing with fjords? Can a cav unit enter a fjord, attack another unit, then move 2 spaces out of the fjord and attack another unit? Or would it only be 1 space due to the movement restriction of the fjord?

Also, can an infantry unit that has moved into the fjord that turn and attacked another unit advance into that units spot if they cause them to flee?

Yes, you can move out of the ford in both cases. The advance/pursuit is considered a separate movement.

Movement is affected when entering fords, not when leaving them.