In each pageview N ads will load onScreen while the other ones will load onScroll.
In details this N can be change via definition with the feature numMadsLoadOnScreen, but in mosaic this is always set to 3.
The load strategy on the details part will be the same as if you open an details from mosaic (this is the logic explained in the previous point). In the other hand the mosaic part will load all the mads onScroll.
There's the option to load some mads in the moment of change between the details part and the mosaic part. To activate that we have to have the feature deepLinkingOnSectionMads in order to specify the quantity of mads.