Sap Web AS 6.40 Installation requirements

We have a 4.6C backend running on Windows with a Oracle database. We want to install Web AS 6.40 (ABAP and Java) on a separate server, and link it to the 4.6C backend, to web-enable some SAP transactions.

Can anyone enlighten me to the platform requirements for installing Web AS 6.40 on the server?

Can we just install WAS 6.40 Kernel and basis component, or do we need to upgrade our instance to ERP2004 in order to install and use Web As?