Which front-end server version and SAP_UI release are required to bring SAP Fiori 2.0 into a landscape?

How does the Gateway and UI component installation differ between SAP NetWeaver 7.31 and 7.4 or higher?

If you bypass Maintenance Planner, which transactions install the software manually, and what does the Planner wizard hand you at the end?

Which two component groups does the back-end server need for SAP Fiori?

For which releases was SAP Fiori 2.0 mandatory, and what could systems on plain AS ABAP 7.4/7.5 enable?

All checks pass for transactional apps, yet KPI modeling for analytical apps fails on the front-end server. Which component was probably forgotten?

Why couldn't an S/4HANA 1511 system get Fiori 2.0 just by upgrading its front-end server?