I agree.
I agree.
I sort of agree.
It is important to make sure that the Photoflo is fully mixed in. I don't, however, recommend that you pre-mix it in quantity.
Instead, I suggest you mix up the Photoflo early in your session, and in sufficient quantity for that session's use. After a decently long period of time (at least 10 minutes), and after the film has been washed, it should be added to a separate container with the Photo-flo in it - not the developing tank, and after removal from the reel. Agitate it briefly, and then soak it for the rest of the time, making sure of even coverage.
It is fine to re-use that same batch of Photo-flo with every roll developed during that session, but it is best to discard it after.
The reason not to mix up and store a quantity of Photoflo is that working strength Photoflo is an ideal environment for the growth of mould!