GUI -> Package - as I think this should be obligatory field - so user should get some message about it.
Of course he could firstly run it - see result - then delete -> specify the package and run one again...

reveng. strategy -> I can't get it work - so should be some more questions here.

GUI -> Main & Exporters tab -> if the dialog small enough - some buttons and controls envisible -> in this case should be scrollbars were.

Generation result -> all files in one place. Domain model classes should be in one separate package and POJO classes in other. User should get possibility to specify this.

Other during generation process - generator simply rewrite my old files - should be some message here. rewrite all or just one - should be clear.