Yes, 45-50 is an acceptable minimum, not the ideal as it slows germination but acceptable. However, leaving the lights on longer hours or even all the time is no problem for the plants, neither is adding a space heater set on low (which is what most do). Adding heat mats after germination - no. Dave

Welcome to the world of ponding! About the lilies, I've kept lilies in 18 - 19 inches of water and they do just fine. In fact, my hardies thrived at that depth. I've also seen tropicals kept at that depth, and they did fine too. They must be pretty adaptable. That's way too shallow and too small for koi, but I think you can keep a few goldfish or mosquito fish if you help shade the water for them in the deeper end to keep it cooler. The lily pads will do a good job of that. A pot with something tall that has broad leaves like taro or lotus placed on the south or west end of the pond would also be a good idea. I was going to say that water hyacinth will do well there, but I'm thinking that they may be illegal in Arizona. They do an excellent job of shading the water if they're legal there. Parrots feather is another option. Pretty much any sun-loving marginal should do well in your pond. Do you have a filter or aeration? Oxygen levels are lower in extremely warm water, so don't overstock your fish. You might also need to add an airstone when temps start getting close to 100.

Btw, in my second comment pics above - just was showing the darker tan cushion color - a couple of examples. Was not necessarily suggesting lime green pillows, etc. Although you do have a range of colors you could incorporate/with various possibilities I would go with your core colors, the tan and black - and use mostly tan on cushions in seating areas, with some white/off white on cushions where it might be possible - as well as some throw cushions with white, black or both + terra Cotta accents, as I showed in my initial comment. Just to again show general idea and some black and white accenting. and lots of terra-cotta ideas above. And I think a shade of blue on umbrellas could be nice.

Please do post a floor plan as @Sammie J suggested. It's difficult to determine the exact purposes of the rooms without seeing how they relate to eachother, the entry to the home, the kitchen, etc. Aside from that, a lot of homes have a "formal" living room and a "family room" or "den". This suits how some people live, but doesn't suit everyone. I would recommend thinking about how you could or would like to use the extra space. Do you need a separate room for TV and reading? Do you need a separate play room or crafting room? Think about how you might like to live in the spaces. It would be better to furnish them in a way that you can use rather than just buying furniture to visualy fill the room.