I was thinking of some peppered cories, actually. I saw some in person and they're absolutely adorable.
I saw that the stocking levels for doing all three species (otos, peppered cories, and CPDs) with a betta were okay, but I'm worried about the filter. AqAdvisor recommends more filtration for keeping them all together, but you mentioned it was a more conservative site. Could I reasonably get away with a Tetra Whisper 30? Or should I back off on the fish if I want to keep the filter? I plan on adding a decent amount of plants before adding new species, so that should help, right?
As for stocking the tank, I was thinking of starting out with just Ahti and getting him acclimated to the larger tank, and adding about half of the number of each species each week after I get some live plants in there.
So I'd get Ahti in, get some live plants a week or two later, add about half of the hardier species, wait a week, add the other half of the hardier species, wait a week, etc down the line
And we're mostly waiting a week each time because of paydays :P my parents don't want to spend too much all at once.