At this early stage it is best to focus on the "core" of the framework to get it right before the first release. (And to get a first release as soon as possible.) One can always add more UI cmponents in later releases.
Yes, but there’s already an AutoComplete widget, so I think it would be a good idea to start at least with a coherent idea on how to structure the various jQuery-based elements (ex. use 3rd parts widgets or use the jQuery demo examples as a base to develop custom widgets etc.).
Agree with that. It would be cool to have this, for instance:
This would really be great!
A datepicker based on jQuery UI is already in the extensions repository