I have implemented an additional tab control to the edit window at the component presentation level for a page using the approach mentioned here : http://www.curlette.com/?p=753

However I need to restrict the custom tab to appear only for a particular publication and I also want the fields in the custom tab to be mandatory and hence I need a way of validating and informing the author if they are left empty. 

My questions: 

1. Is it possible to restrict the custom tab to appear on pages of a particular publication? If yes, how do we achieve it?
2. Where to validate for the mandatory fields under custom tab?