With honeys you should be getting a group, not just one.
Though not gregarious in the sense of schooling fishes it does seem to require interaction with conspecifics and displays more interesting behaviour when maintained in numbers, meaning the purchase of no less than 4-6 specimens is recommended. Groups develop noticeable hierarchies and you’ll often see dominant individuals chasing away their rivals at feeding time or when occupying their favorite spot.
If you can manage to get all male guppies, that will help. The same would apply to Platys. By eliminating the mollies you also eliminate the potential for them and the guppys to cross. Since platy and guppy are different families, they can not cross in terms of producing fry.
6 pandas will be fine. The rule with schooling or shoaling fish is that more is always better as long as it is withing reason considering the other fish and the size of the tank.
Otos are about the least aggressive fish you ca get. The biggest issue folks have with them is insuring they get enough food once they have cleared any algae/diatoms from a tank. It is also important when you buy them to make sure they do not have sunken bellies. If you are getting them from a store it is best to wait for them to have been in the store tanks for a while so you know they are OK.
Are you considering live plants?