I think I can explain all of the underlined portions but for the storing of yeast at cold temperature. By "cold temperature", I am assuming that refrigeration is intended. However, from what I understand, if dry yeast is kept in the refrigerator in a tightly-sealed container, it should last about 6 months. I suspect that there will be progressive diminishment of its leavening power over that time, but I don't know at what rate. This is never an issue for me because I freeze my dry yeasts. I would never keep the yeast in the refrigerator for 6 months, although I might put an amount that I planned to use in a week in the refrigerator and put the rest back in the freezer. Maybe that is what the portion underlined is intended to mean.
The rehydration of IDY when used in high speed mixers is quite common. I am fairly certain that the types of mixers SAF has in mind are VCMs (vertical cutter mixers) and Robot Coupe mixers. They have large bowls and operate so fast that rehydration of IDY is recommended to get adequate dispersion of the IDY. In addition, the water temperature has to almost exactly 95 degrees F. To the best of my knowledge, these are the only mixers (and quite possibly only the VCMs) that apparently require rehydration of IDY. Whether the concept should apply to food processors is an interesting question, but I suspect that the very small bowl size of food processors pretty much insures that there will be adequate dispersion of the IDY.
As far as contact of IDY with cold water is concerned, neither ADY or IDY (or even fresh yeast) likes to be shocked with cold water. Doing so will affect its metabolism, leach certain soluble cell constituents from the yeast (primarily glutathione), reduce enzyme activity, and otherwise degrade the yeast’s overall performance. However, if the dry yeast is thoroughly blended with the flour, the cold or cool water will be absorbed primarily by the flour and thus have less direct physical contact with the yeast. Alternatively, the dry yeast can be combined and left in the flour for around 30 minutes before adding cold or cool water, during which time the yeast will absorb moisture from the flour (which can typically contain about 11-14% water) and commence rehydration before the cold or cool water is added. "Cold" water in the latter context usually means water that is not frozen. In fact, in hot climates, ice is added to cold water to get its temperature down so that the finished dough temperature is at the desired value. VCMs as mentioned above work so fast and generate so much heat that the bowls have to be cooled down before using and this is usually done with water with ice added.
What the last underlined portion refers to is the need to adjust the water content when substituting one form of yeast for another because of the difference in weights of the two yeast forms. That is much more important where large dough batches are concerned. For home pizza dough makers, the difference in weights of say, ADY and IDY to achieve comparable leavening power is so small as to be negligible. For typical home batch sizes, you may not even be able to measure the difference as a practical matter.
Lydia, when I clicked on the link to the article about freezing dough, I did not find the article. Is there another link to the article?