Would definitely be useful to know answers to these.
I hope the 'Smart' SAPUI5 objects will have better Annotation support from HANA XS OData service in subsequent releases. In the meantime I have now managed to get it working by:
- creating a custom annotations XML
- use the mockdata server to read the XML into a temporary model
- copy the Annotations from the temporary model, to the main model (which uses the XS OData service).
It's not pretty but seems to work for both Smart Filter and Smart Table.
I’ve also noticed that sap.ui.model.odata.v2.ODataModel supports adding a separate annotationsURI, but haven’t managed to get that working yet.
For analytical Apps I also like the idea of using ExactBrowser but haven’t seen it covered yet in either the Fiori design guidelines or by Smart Business Cockpits. It also requires quite a bit of code to use so would benefit from being ‘Smart’ enabled before widespread use.