Hi San,
Our team have worked on few POVs in ABAP on HANA area. Most of the links above are quite useful in terms of Best practices documents.
As part of POV/POCs one can select few critical ABAP reports (suggested from Business) that have performance issues, use SAP tools to find out problematic - hot spots within the program that have issues, correct the same through code push down. This can be done by creating calculation views or Analytic/ attribute views and/or Stored procedures and consume the same in ABAP reports.
Important step would be to measure Performance improvement figures through SE30 or any other tool before/after Code optimization.
If you have any specific queries in Code push down or POCs in ABAP on HANA, you can post the same here .
Regards,
Suma