Enhancement package upgrade

Dear all,

We are planning to upgrade the SAP ERP system Enhancement Package6 in  ECC6.0 ERP system.

Source ERP: ECC6.0

Target verions: ECC EHP6

1) Is there any impact of  other environments[BI, PI, & Solman] depend on level of applied EHP6 Version in ERP system.?

2) Is there any impact in design of connection with other SAP system like     Connecitivity to the SAP solution Manager sytem ,Centralized user management, PI system?

3) Is it necessary to upgrade the (ST/PI, API) in Solution manager ?

Thanks Thiru.