That's a lot of questions!
My heater is resting on the foundation slab of 35 cm reinforced concrete. I cut a rectangle in my living room (i think my wife should get some kind of recognition for letting me do this!) larger than the footprint of the stove, got down to the concrete subfloor, and poured a steel reinforced slab of vermiculite concrete larger that the heater to distribute the weight more. On further thought, the vermiculite was probably unnecessary as the heat travels up more than down in the heater - the bottom courses don't heat that much. I made friends with the refactory people and used the proper mortar for the job. I have an expansion joint of cardboard all around the heater which turned out to be insufficient - i do get cracking but not that bad - i plan to patch it when it's hot (plans, plans, plans). I put a layer of ceramic wool as both an expansion joint and a way to moderate the thermal transfer in places where I learned the heater gets hottest - no cracking there! I also had a friend construct a heat exchanger and built a self enclosed box on top of the heater for DHW. I have not been able to entice a plumber out yet to hook it up, but I hope to take care of that soon. But measuring how hot the heat exchanger gets, I should have plenty of hot water.
I'm not sure what you mean when you ask if is conforms to standards that would qualify it as a masonry stove. I built it right out of the MHA portfolio, and the design is that of a finnish contra-flow. I received much good and needed advice from three of the top builders out there. Has it been inspected by the authorities and conform to local building standards, is that what you mean? I live at the end of the world, and it is highly unlikely that any local standards apply. You're right, I've only used it a couple of winters, and only time will tell if the materials were correct, if my workmanship sufficient for a worthy piece of work. And perhaps I'm too stupid to be cautious - quite possible, but i do have two CO monitors in the house and I'm careful not to overfire it. Time will tell.