How does the app-type architecture change when you move from SAP Business Suite to SAP S/4HANA?

Which two components run in the SAP HANA XS engine in a classic analytical landscape, and where does their content come from?

In the integrated SAP HANA XS landscape scenario, how do the ABAP back end and SAP HANA XS share infrastructure?

Which classic Fiori app type requires SAP HANA XS, and what role does XS play for it?

Which app types does a plain ABAP environment support, and how does SAP HANA as the back-end database affect that support?

For analytical apps, which two parts of the KPI modeling framework sit on the ABAP front-end server, and what does each do?

Besides business logic, what does the ABAP back-end server own in a Fiori landscape?