EBP 4.0 to SRM 5.0 -- Upgrade/Installation. Best Practice

Hello Experts,

My Client is currently on an EBP 4.0 system and chooses to move onto SRM 5.0

Would request your opinion on ..

(1) Would an upgrade be advised or a fresh Installation

(2) A list of "nice to have" features in SRM 5.0

(3) How can the existing data be migrated

Thanks in Advance.

AjitK