Running makes all the difference to getting over the chasm (and the bridge)! I finally completed the 'Creaky Cave' but with only 1 star. When I went back to do it again and find them all, it gave me the one star at the start. I assumed it would make me find them all again? Is it supposed to do that?
I also noticed that just before the chasm, one of slugs and one of the red monsters run into each other and get stuck. Neither can move forward. And neither tries to go back or around. I recall there being another instance of this later on that level too.
If you have 3 hearts and collect another, it doesn't increase to 4. I assume 3 is the maximum so I would have thought it would just leave it behind? Or have no maximum?