You're trying to find secrets in a game that doesn't have a killscreen.
As far as getting the swarm, I have a theory that the odds increase the higher Donkey Kong is on the ropes.
Look, there are at least three people in the hobby I think that can beat my record(s). Barra, Jason V, and Wags.
I'll tell you what matters most. Practice. It's really not that complicated. The more time you spend playing the game, the better you get.
Gil, if you are as fast of a learner on DK3, as you are on DKJr, you'll have not much of a problem. Again, it's all about the practice. That's the true secret ingredient.