3 Questions regarding Kontact's holiday management

Hi everyone, 3 questions regarding Kontact's holiday management:

(1) I'd like to edit the pre-set holidays (which one can choose from the menu 
Configure Kontact > Calendar > Regional > Use holiday region: xxx). How do I 
that?

(2) Is it possible to add an additional holiday region? How can I do that?

(3) Is there a simple way to add a list of personal reminder dates (as 
holidays)? How?

Thanks for the help,

homoludens