2) Upselling is offering options, more expensive options. It is not necessarily bad, and it may be quite good, as it allows people to choose better products for a higher price. The point is that Tim Cook likes doing it (and the bad thing is, perhaps at the expense of releasing new products).
3) Yes. The Pro is almost a year old now. But there are still no signs of a refresh, so they will co-exist for some time.
4) Value is subjective. Overcharging is objective. A 1 TB PCIe 4.0 SSD costs about $100, and that is with all the packaging. Apple sells the same additional 1 TB for $400. You may agree to pay the price, or perhaps you do not care. But Apple is definitely overcharging here.
5) Apple did not. One analyst once claimed Apple would launch a $2,500 display aimed at consumers. It is more a companion to the Mac Studio.
6) Apple's website currently lists the iMac as the iMac 24", which may suggest another version is in the works.
7) Perhaps some XDR Display Pro customers may feel ripped off.