Hi,
You don't need the land bit if they are axolotl, if you are sure ( check pics on this site) I would remove it. With regards to flooring I have started of with sand, but as I have had a long spell of the water cycling a while back a fair amount did get sucked up leaving patches of bare tank, I would now be tempted not to add any next time I up grade the tank as it is a lot easier to spot clean ..though if I do add more I'll get lighter coloured sand as a personal preference. I have recently replanted all the living plants into pots with sand as they like to play with the plants I was constantly having to re plant, this has been succesfull over the last 6 weeks. You do need some where for them to hide, I bought from the local aquarium a lovely cave which they can BOTh hide in, but hubby was unusually alert piped up " you said they tend to be solitary so you must have two or three hiding places", so I left the original drain pipe in and on the whole they lurk singley in either one ( how on earth they actuallt manage to turn round in the drain pipe is a mystery to me!).
With regards to the gill colour, my golden ones gills are paler when she is still, maybe asleep or relaxed, when she is in food mode they go redder, with my wild type they seem to stay black. While in the pet store thay may not have been very happy, so may possibly have been redder due to stress or anxiety ( much like me!!).
Hope this helps.
