6-8 pellets a day is perfect and Hikari pellets are a good choice.
Caution on the chicken though.... this is not a natural food for fish and should be fed very very sparingly. Also, it must be very lean meat with no fat, as fish cannot process animal fats very well.
Frozen bloodworms make an excellent, easy treat once a week. just thaw out part of a cube and feed 5-6 of em. All my fish go nuts when the bloodworms come out
I've always fed my bettas Top Fin Betta Bits. But that's because it was the first food I've ever bought and it was a huge container, so I don't think I'll run out any time soon. I feed them 2-3 pellets at a time 3 times daily. My bettas love it. They also love their brine shrimp.