Check out the 8 direction Behavior with default controls turned off.
1. You would check if the x value is greater or less than the swimmers x and simulate that direction in the behavior.
2. Simulate the direction s=<- d=->
3. Use a variable for health. Lots of examples in the help, and tuts section. Use Sprite frames.
Edit: C2 not C3
TileMovement Behavior would be better
Bummer.