[itimpi]

At the moment the Nook driver apparently does not realise that FB2 is a supported format for the Nook. This could be added in the short term by patching the Calibre source, although longer term I expect it will be added as standard. Once FB2 is added as a supported format then it should be possible to customise the Nook driver as to what is the prefered format if both FB2 and ePub are found.

News is always generated in whatever you have set as your default output format. It is not possible to specify a format that is specific to a news source. It is an interesting idea and it might be worth raising a ticket for this as an enhancement request if you think it is worthwhile (but even if it is accepted I cannot see this being done that quickly).