Re: Fly orientation.
What you see there is a style of fly, hooks riding up are a good choice if you have a lot of rubble on the bottom; saves a lot of snagging. Now if you fly is running a little off bottom you don't have to worry about snagging as much.
As far as real insects, I believe if they get washed off their holding area they will tumble in most cases. There are some nymphs that are very good swimmers and they will swim about in the bottom rubble.