CRS and CBS are fine together. They're the same species, but the red is recessive. The offspring will be half black and half red.
Not sure why you're going with the CO2 and high-tech route... Seems like too much work to me.
For fauna, A Betta will devour your shrimp. I would go with tiny fish like neons/cpds, or stick to an invert tank:
Cambarellus patzcuarensis sp. Orange (ie CPO)
Choice of Red Cherry, Snowball, or Blue pearl (since they WILL breed, and it's ugly.)
Maybe even add some rabbit snails
and *gasp* my favorite invert of all that I wish I had right now-
thai micro crabs