Hiding the subscriptions list
A couple screen shots:
You can hide and show the subscriptions list manually via the View menu: choose
Hide Subscriptions List (or Show, of course, depending on its state). It has the same keyboard shortcut as Mail has for showing/hiding mailboxes.
The way I use it is to have it hidden and show automatically. When viewing a web page, it hides. When viewing a news item, it shows. Choose
View > Automatically Hide Subscriptions.