On Snoopy's leaf-collecting mini-game, they are supposed to fall by themselves. There was a persistent glitch that prevented the scene from running properly. If the leaves don't fall, you may have to restart the island (small map at upper right).
uh, you don't. you wait for it to fall
You don't. You turn back to the right and go down the slope, then back up past the rabbit holes.
You get him to organize the leaves in a pile, by blowing on them as they fall. Start at the right, and when one drifts down, click to blow underneath it to steer it left, onto the pile.
Just click on them before they go back down.
Stay behind the pumpkin all the way from the log to the playground. If you leave it, it will roll down out of play to the right.
Cross the holes when each rabbit ducks down. It will be a few seconds before they pop back up. Just don't leave the pumpkin on top of a hole.
When you reach the cliff, stop the pumpkin. There is a ramp leading down, with a pumpkin flag checkmark.
Play the football scene with Lucy and Charlie Brown. Pick up the football and use it at the doghouse.
The first drop cannot be negotiated - you have to turn back right and go down one level, then continue left to where the rabbits are. The final drop requires you to slow down as you approach the swings.
When you get the football, go left to Snoopy's doghouse and use the football. It will knock his flight helmet and goggles down from the tree.
Get close to the first girl (right side) and stop. When she swings backward, all three kids are going back. Quickly shove the pumpkin left, past all 3 swings at once. Don't slow down.
You have to weigh them all, two at a time, to find the heaviest one. Start with the two on the left, and go right, each time leaving the heavier one (moves down) and replacing the other one.