Blood shrimp are absolutely not territorial, and many peoples experience, including mine is that if you get a single one they simply disappear and don't come out.
Rainfords (Court Jester) , and the similar Hectors are prone to starving to death in small tanks, especially if they haven't been left to develop an adequate microfauna.
DSB = Deep Sand Bed, and pay or may not have a Plenum. Plenums, from the Jaubert school of filtration and not especially in fashion nowadays. DSB's are, depending on who you talk to.