I personally wouldn't put any shrimp with a betta. Bettas are carnivores, and shrimp just look like a meal to them. Shrimp are also more likely to stay in hiding when predatory fish are in the tank with them.
Apples snails are not asexual, and require a partner to reproduce - however, they are poop machines, and do add to your bioload. Nerites may lay eggs in a FW aquarium, but they can only hatch successfully in brackish water.
I'd get a couple of nerites. The bonus is that they love algae.
You can't change the music of your soul. Katharine Hepburn