I guess, Bjoern Woppmann has responded to above queries on this blog. There is a Gateway for that ...
I think the handling of an OData service is much leaner compared to a SOAP service. Also, there are some restrictions when using SOAP via Integration Gateway, that don't exist for the SAP Gateway (ODC) Data Source.
Regarding the licensing, my colleague Martin Bachmann made the following statement: Re: SAP Netweaver Gateway Licensing:
in general there are three licensing options:
1) if you already have Business Suite users then GW is part of this license
2) if you need users for e.g. a new group who have no SAP licenses you can use the SAP GW User license (we have a 'productivity accelerator' version of the license that can be used together with e.g. Duet Enterprise or the Productivity Accelerator Apps).
3) if you have a scenario where you do not need names users (anonymous access, ...) the GW Consumer Access License is required (metered by service calls).
Regards,
JK