Toad lilies don't need to be continually moist. I grow them in 3 different spots and I rarely see them wilt even in afternoon sun. If I remember correctly, each stem or two is its own little plantlet with roots. As for how many to plant in a square foot, it would depend on how fast you want coverage.
I did see that it's supposed to turn cool next week. Today was a scorcher for May. My thermometer (remote digital) read 87 this afternoon.
