How to create page and restrict it to authenticated users? I'm using the empty_page module to create "myhome" page and show blocks with a user's own content. That page throws an error for authenticated users.

How can I create an empty page in code and throw a 403 error when a visitors tries to access it?
You should try the Frontpage module - it allows you to set different home pages for authenticated and unauthenticated users.