Clock Domains and Clock Domain Crossing (CDC)

The whole point here is to guide the Fitter after cutting timing between the two clock domains, so the answer to your first question is yes.  The two domains are cut from each other and then set_max_skew and set_data_delay are used to define skew between bus paths between the clock domains and the data path delay between the endpoints of the two sides of the cut paths.

As for the values to use, just use the recommended values you show in that slide.