Workflow set up with event receiver

Hi Experts,

My scenario is like this -

I am doing a customer outbound interface. The business objects KNA1 & KNB1 are extended to create events for creation & changing the customer master.

The change documents will be configured to trigger these events whenever a customer is created or changed.

Now HOW DO I DO THIS - I need to develop a multi-task custom workflow template as an event receiver. The workflow will do the following :

a) Will check if the customer exits

b) Will collect all the information petaining to the interface

c) will call the RFC -enabled FM's to interface the data to a Middleware.

d) Will write to an error log if the interface failed

Please suggest me & your valuable solutions are rewarded with points.

thanks

Harikumar