I'd suggest getting a dial type METAL thermometer. It costs few times more than the glass type but reaction time is so much faster, getting developer solution to the right temperature much easier. Trying to do that quickly with glass thermometer is very frustrating because of the reaction lag.

Discussing development time online is waste of time.... every little bit of variation in exposing and developing (technique) will cause changes sufficient enough to affect the "perfect" time. Just start from what's published and go from there. Unless you *really* screw it up, you will get usable and good result and from there, it's more of personal preference.

I'd also suggest spending some quality time with Kodak's technical literature about most of your chemicals. A LOT of your question is answered there in depth.

About Photo-flo, for some, including myself the standard 5ml to 1 liter (1:200) dilution causes drying marks. I use half that now and it works much better.