I have looked at the docs of both the products briefly, but cant seem to come to a conclusion if
A) CUMA is a superset of CUM
B) CUM and CUMA provide similar features (with the added capability of CUMC smart client on Blackberry) but CUMA is not a full superset of CUM.
Can anyone please clarify ?
No it doesnt. Both are two independent products and completely different features. To make CUM work, you need to purchase Callmanager 6 (as its bundled in the CM6 software itself). To enable CUM functionality for every phone you will need extra DLUs.
CUMA is a separate product which you will have to purchase if you want its features. Currently CUMA requires the advantage and proxy softwares to be run on two different servers, but this is going away soon and will merge into one server.