I'm not super familiar with fish-only tanks, but I'll offer my opinion.
First of all, if you intend on having a DSB
, then yes, by all means, put it in before you add livestock. Adding sand can cloud the water considerably, and adding live sand can often trigger a small cycle.
I question the compatibility of the Coral Banded Shrimp & the Blood shrimp together. The Coral Bandeds can become pretty nasty, IME
, and are not always compatible with other decorative shrimp.
Electric Flame Scallop, IMO
, is a poor choice in any tank. These have a very poor survival record - almost always starving/dieing within a year.
Electric Blue hermit - no personal experience, but I've heard tales of these hermits being particularly aggressive. Mostly toward other hermits and some snails.
Arrow crab - In my personal experience, these will
attack and kill any and all hermits in your tank. They are very aggressive (and creepy!) by nature.