There's an annoying textbox as you enter this room that I just mash through, starting Kirby's float in the process.
It's faster to change back to fire before grabbing the chest, because your stomach is disabled for a few seconds while the chest is still bouncing around inside.
If you manage to grab the chest and use the fire bubble at the same time, the fire bubble gets duplicated and the screen will turn white. This gives you an extra bubble to, e.g., mix for wheel.
It's actually faster to spit out the first chest before grabbing the big chest. This will cause the usual cutscene to play instead of the long one that introduces the entire Squeak Squad.
Grabbing the Candy earlier in the room makes it easier to hit this chest, though I wonder if it's really much of a hassle to skip the candy altogether.
It appears to be faster to go around the blocks instead of headbutting them.
While Storo is napping, you have enough time to grab the fire bubble and break the bomb block.
After obtaining hi-jump, the room in the middle of the left path contains a chest.
It's easier than it looks to hi-jump straight to the chest.
If you're fast enough, you can hit the switch, grab the chest, and reach the exit all in one go.
A visual cue for when Dedede's invincibility frames expire is simply the moment his sprite changes when he gets ready for attack.
The chest will drop in from the ceiling, so it's best to grab it as soon as possible.