SC and PO workflow

Hi

I am new to SRM 7.0. My requirement is like this.

My workflow(WS40000014 N-level approval) needs to be triggered when Shopping Cart created or PO Changed.

I am using BADI "BBP_WFL_APPROV_BADI". But this for Application workflow not for Process workflow.Anyhow its working fine. But problems are below.

1). How add a reviewer in SC or PO workflow if total amount morethan 250K USD?.

2). I want to send a notification to manager when a workflow is pending with a approver for morethan 3 days. How is possible?..

3). When PO is changed, then its should restart from 1st level approval..

4). If there is 5 item, then workflow should goto 5 item level approval.

Please tell me how to achive above things in SRM7.0.

Regards

Ravi