Cr. regani is the only common dwarf pike I'd try in a 30"x12" footprinted tank. I do use 20 longs but divide them if keeping more than one pike in them. Most dwarves deffinately share their bigger siblings intolerance of each other. Cr. regani seems to be differant though, many people have grown them up, paired, and bred them in a 20 long.
As for breeding, noto's require strict water requirements ... along the lines of heckel discus and altum angels they are found with. Though mine did fine and grew in only 6.8 pH water, I didn't get any breeding activity. For the Cr. compressiceps, well the male was too busy trying to kill the female in the 40 breeder for spawning to even enter his mind, vicious little fish. Cr. regani has been bred several times, since most forms are white to clear water, water requirements aren't crucial, just low nitrate and lots of water changes (tefe variant is probably an exception though, blackwater).
Except for Cr. compressiceps, I wouldn't try other dwarves with a gold saum due to their shyness. If it were me, I'd go a midsized pike like belly crawler or proteus.