10 would be great! They're so tiny, I think you'd be fine with 12-15. On Anders' 10 gal stocking list that's stickied in the stocking subforum, it lists a max of 12 for all of the Boraras species, but having kept both B. maculatus and B. brigittae, I think up 15 to B. brigittae would be fine - they're smaller and more slight than B. maculatus, so I think more would be fine.
So you could do 12-15 and 10-20 shrimp (to start - they'll breed and soon you'll have lots)? I don't think having more chilis means that you can't have more shrimp too.