I'm going to be a little serious here, and suggest that you should actively avoid engaging with anything that might keep you on the toilet longer than necessary to do your business. That position puts a lot of strain on the rectum and anal hemorrhoids, and can exacerbate health problems that tend to go hand-in-hand with desk jobs.
Oh, absolutely. The upshot of my comment was "avoid things that put undue stress on your rectal muscles", which includes both straining and spending extended periods sitting on the can.
Absolutely do not stand on the seat. Beyond getting dirty shoes all over the toilet, the asymmetic force during initiation is a great way to break the toilet seat or overcompress the wax seal beneath the toilet (I had an ex-roommate damage my toilet this way). Putting your feet on the rim is a good way to slip and fall. If you want to simulate a squat toilet with a Western fixture, raise up your feet on a step stool. Sit down first then raise your feet. </rant>
Sometimes you are in a public place with nothing to use as a platform. Never use the seat, of course, since other people put their butts there, and as you say they can be fragile. I use the rim. I have never slipped or fallen. It is quite secure.
I always joke with my friends when I tell them the girls in Asian countries always have more shapely asses than their Asian-American counterparts. That's because they work out their asses when they need to do their business.
That said, this app is frickin' hilarious.