Betta Fish: Blind Betta–Advice?

This is Matt Murdock. He's a male samurai–almost two inches long, very shiny, and at least mostly blind.
In the first picture, he is acclimating in a measuring cup. In the second, he is viewed from above just after a big meal (through a lid).
I got him a few days ago; I saw him in a chain store while scouting guppies, noticed his diamond eye, left, worried, returned, and nabbed him (the wonderful gal was also worried for him and sold him for half price when I pointed it out; she said she wanted someone who could take care of him to get him).
I'm doing a fish-in cycle (I know, I know. I'm testing water twice a day & using water conditioner) in a twenty (US) gallon tank with 15 gallons of water in it (didn't realize my big filter didn't have a cartridge; using a little one that requires lower water levels). The tank is equipped with a heater (set to 78F), terracotta pots (plucked from guppies), some driftwood (plucked from empty guppy quarantine tank), gravel (also plucked from guppy quarantine tank), and live plants (non-chain lfs or guppy tank) including java ferns, Amazon sword, moneywort, frogbit, water lettuce, and a tall grassy thing the guy couldn't name.
Murdock has been very active, but there's a lot of glass surfing–he's new to the tank, so that's expected, and he's blind, so I guess it's extra expected. He's also made two small bubble nests–one by his heater and one by his filter. To me, his fins look fairly healthy; the picture doesn't quite do him justice. When he's swimming, they compress like an accordion and are a simple, stunning black, but at rest, they fan out into black and silver stripes studded with black spots. One ventral fin is forked at the end, which I think is a tear, but I see no signs of fin rot, ich, or velvet. I have not seen him flare. Referencing the chart regarding betta weight (dorsal view) has led me to belief Murdock would classify as "thin," a mark before "ideal."
I received two sample feeds. The first is Nutrinsect (47% crude protein) and the second is labeled "Betta Shrimp Patties Ultrafresh" (between 38 and 50% cp. Results uncertain). I also have flakes for my guppies (47% cp, first & fourth ingredients animal-based) but haven't tried those with Murdock. I've been feeding a mix of Nutrinsect and the shrimp patties0 every morning and night with varying success.
Getting food to him has had a bit of a learning curve (fairly new to bettas and, again, he's blind) but I've stalked around forums and experimented, and found a method that works for both of us.
In the far future, I would like to add a small school of corydoras to his (20 gallon) tank to give him something to interact with when I'm not around. I was also thinking they'd clean up any food he misses and I can't find, and they'd be shy enough not to bother him too much. I'm looking into bronze (hardy), emerald (beautiful), punctactus (just very cool) or hasbrosus (small).

In regards to experience—
I have been keeping guppies for several years. I also have had a handful of disabled animals, including a blind cat, two one-eyed cats, one crippled cat, a gimpy chicken, a one-eyed chicken, a gimpy turkey, and a scoliosis guppy.

My current inquiries regard the following:

Tank setup (for blind betta specifically)
Tank mates (again, blind. Cories = good idea or bad)
Enrichment (blind, don't want him bored)
Nutrition (published research is limited. Seeking numbers on TDN, NFS, CP, and mineral requisites)
Ration size (how much food? Some say 3ish pellets, others say eyeball size. Diameter of eye? Area of eye? Volume of eye? His eyes are much bigger than the volume of three pellets)
Meal timing (twice a day? Should he fast? How often? Wait to fast until he's thicker?)
Health (common afflictions + prevention, diagnosis, & treatment)

I want to be sure he's living his best life. Please point out anything I missed so I can ensure his health.