If the camera's still available take as many as possible. That last pic of the octopus in hand is quite a bit larger than mine. But looks pretty close to my Einy. He's almost always dark red, and has a dark spot on each side of his mantle, behind his eyes toward the tip.
They are what is being called O. mercatoris. Whether that holds up when the molecular data come in remains to be seen, but they are definitely the common Gulf dwarf that I have been rearing. They are a big egg species and very easy to keep. However, they are nocturnal and secretive.
oh, i know a food source, i dont know how big these guys are when born, but if you go to the beach, that floating sargassum weed is packed with small sargassum shrimp, crabs, and sometimes fish (the fish are a little big for your octos though)
just grab a large chunk and put it into a bucket (i would collect as much sargassum was possible) then when you get home but a heater and a Powerhead in the bucket and whenever you want some shrimp just grab a patch of sargassum and bring it to an empty bucket.. then shake it out really well (replace the sargassum into the holding bucket just in case there is still some shrimp/crabs on it)