It sounds like what you saw were freshly hatched/emerged mayflies that were using the suns rays to dry their wings out. Based on this hatch chart http://www.frontrangeanglers.com/Fis...vrainhatch.htm
the only mayflies that could have been hatching then are red quills or green drakes. I'm guessing if it was either of those two it was the red quills, as they're not all that red, and green drakes are not small.
That hatch also could have been another bug altogether, another mayfly or possibly even a caddis. Mayflies fly much more gracefully than caddis do. Caddisflies fly much like moths, which reminds me of an old joke.
q: How can you tell when a moth/caddisfly farts?
a: it flies in a straight line
The hatch possibly could have even been a midge hatch. I have found that many times hatches of large midges can look like small mayflies.
The "sometimes touching down " you saw was actually them dropping their eggs into the water, which then sink to the bottom to grow for a year before they start crawling around as nymphs.