Netweaver Standalone vs on an application server

I am working with a client who is interested in implementing Netweaver Gateway on a standalone server.  Typically Netweaver Gateway is installed on an existing application server. 

Could someone please tell me the difference that I would see technically if the client did this.  Would I still be able to import RFC's and BAPI's which exist on the current ERP or CRM system?

Any education / details you could share would be most helpful -

Thanks,

GD