Neon tetras, they're a bit active, and a bigger shoal of them would be better + it'd look better, a 20g would be way better if you wanted to do the tetras like neons, cardinals, rummy-nose, etc.
Ember tetras are nice and small for a 10g. I have some in my 10g.
Shrimp, depends on what kind of shrimp. Ghost? RCS? Amano? Most important thing is to give them cover if your Betta attacks them, dwarf shrimps like RCS could be gobbled up easily by a Betta.
Otos, unless your tank is a mature cycled tank with lots of plants I would not recommend these guys. They're very sensitive to water parameters and eat a lot of algae.
All in all your tank is overstocked with that many fish in it.