You might want to check out the following links for Axolotl keeping:
www.axolotl.org and
www.caudata.org
They have tons of info on how to keep Axolotls; both sites would caution that the gravel that is in the tank right now is small enough to cause intestinal impaction; Axies will eat just about anything that can fit into their mouth (they "gulp" food with a vacuum-like effect, and it is easy for small gravel to get sucked in by accident).
I know this is a fish site, so I'll keep it short, but those sites are great for information.
Good luck to you.