Portal landscape

Hi ,

We are planning to create SAP Portal Landscape with below components

1.AS Java

2.BI JAVA

3.EP

4.EP CORE

5.DI

We are planning to use one portal instance for all our business needs.

is it suggestable to use E-COOMERCE and SAP BI in single Instance.

Regarding NWDI server components required to deploy EPD,EPQ and EPP or one seperate instance(AS JAVA +NWDI) fulfil our requiremnet. which is the best way for basis point of view

Please suggest if the above scenario is best or required to seperate business areas and create more instances

Thanks & Regrads,

Subba Rao