Here's a hint on the climbing/leaping:
When you're on a tree, hold down the direction you want to leap in, and then press jump. Then you'll jump in the desired direction.
If you keep the jump button held down, then you can swiftly leap from tree to tree to tree continuously (assuming you maneuver in mid-air properly).
If you just press jump without holding down a direction, you'll just jump away from the tree in the direction your back is facing - this allows for accuracy when jumping in a specific direction.