Upgrading from SAP 4.6 C to 6.0 ECC

Hi

I want to know a brief description on Upgrading from SAP 4.6 C to 6.0 ECC. It mean like

How to Analyze and check migrated programs in 4.6C.

How to Maintain the issue tracker for the objects which contains data and table related problems

How to Replace the population of BDC screens, fields and OK codes which differ from the BDC flow in the target version from that of the old version

How to Replace the Function modules which are obsolete in the target version with a similar Function module or a method with respect to functionality

What is know the Performance EPC to identify any new errors after changes are done

Pls reply it helps me a lot.

Thanku

Regards

Murali