Best approach in implementing BW on HANA with S4HANA source system

Hello,

We are going to implement a project in SAP BW on HANA (7.5, bi cont 757 sp>17) with an S4HANA source system (1610).

We need the standard reports for the main modules but also are going to implement a lot of custom data flows and reports.

My question is - what would be the best approach in implementing?

Should we use the new HANA optimized BI content? SAP ODP extraction?

Could we still use the classical BI content flows (7.57 sp>17)? And the classical source system type SAP?

If we decide upon using the 'classical' implementation, will it be possible to migrate in the future, maybe to a BW/4HANA?

Thanks in advance,

Andreea D.