ESS / MSS Implementation

I have couple question regarding ESS / MSS implementation.

We are currently planning on a ESS / MSS implementaion with 4.6c version for R/3. and EP 6.0 with ITS.

1. We are planning on migrating to my SAP ERP and SAP Netweaver 04 with WAS6.4. What are the implications on a future upgrade to my SAP ERP ( 5.0 version) from R/3 4.6c and EP 6.0 with ITS ?

2. Are the business packages for 4.6c/ITS/EP 6.0 combination significantly different from mySAP ERP 5.0, SAP Netweaver'04 WAS 6.4 significantly different ?

3. Is it worth waiting for the upgrade from a functionality and user interface standpoint ?

Thanks

Sarina