Still can't help with quantity of live food other than enriched full sized artemia where I feed about a half tablespoon of them to five abdominalis and the same amount to 8 barbouri. (per feeding)
For me, mysids terminology I use for the saltwater shrimp that are normally found in reef tanks, and mysis I use for freshwater shrimp like the frozen Hikari and PE we use for general feeding.
Ghost shrimp (glass shrimp, grass shrimp) are freshwater shrimp that many hobbyists use for feeding seahorses but have to be added at feeding times because their lifespan once introduced to the salt water isn't all that long.
I haven't used ghost shrimp in over a decade now, back when I had reidi and they used to tear apart the shrimp and eat the pieces if the shrimp were too large for a quick snick.
I had tried them with angustus and barbs also but they only ate the smaller ghost shrimp and were not interested in the larger ones for the most part.
For a few years I cultured salt water mysid shrimp and it was very labour intensive because of the high cannibalism rate, requiring separate tanks for the nauplii each week as any larger ones ate the smaller ones big time.
Whichever live food you choose to use is made much better by enrichment just prior to using as food.
You can get both artemia and ghost shrimp from
https://www.livebrineshrimp.com/