Bookstore Etiquette

As much as I frequent bookstores, I’m never quite sure what the proper rules of procedure are. Can I sit in a bookstore all day and read whatever book I choose front to back? Am I allowed to talk softly on my cell phone? Am I allowed to carry on a conversation with the person I’m with? Can I sit in the bookstore café and do homework or read books without buying anything (my primary question)? When I’m done looking through my stack of books should I put them back? This doesn’t have to do with etiquette, but is it wrong that I browse through books at a bookstore only to purchase them on Amazon? Just curious.

Side Note: As I’m sitting here (in the bookstore cafe) with my Italian soda (not because I wanted one, but because I felt obligated to purchase) I notice a guy cutting and eating a peach… is that proper etiquette (bringing own food)?

That is all.