I would put a hose bib in the room as well. that way you can hook up a hose and wash everything down if you need to.also put a 2"P-trap not 1.5" in the floor ... less likley to clog and easier to clean out.
make sure the plumber puts a primer on the p-trap to keep water in it so all the water dosent evaporate and the sewer/septic gasses dont come back into the house.
I would have the electrician put a seperate pannel box in that room so you can put as many breakers as you need for power and you can buy the GFI breakers for it instead of having the little ones in the wall on the socket.
have the electrician run a 3" or two 2" conduit under the concrete from the pannel box to the tank underneath the concrete and up the wall 32" so you can pull as many lines as you need for power.Just make sure you have atleast a 200 amp service to the house.
also have the electrician run 3 or 4 sets of conduit from the
pannel to over head of the tank for your lighting itll be much cleaner and allot less wires hangin out..
if i think of anything else ill let ya know.
Robert
p.s GET A CHILLER dont rely on the house AC unit. for the money your going to be spending on this tank its a small price to pay that way the house ac dosent work as hard and youll have peace of mind... the best thing i ever did was put a chiller on my tank...