We did a book event in a town where I used to work in. I emailed and Facebook messaged people that I used to work with. Only two showed up, but they both bought books and we made enough to pay our table fee and a little profit just from those two people. So it can help.
Oh, another thing you mentioned... getting our books vertical doubled our sales. I would not have believed it. And Matt would like my latest book where the main character dies on the first page. Ha ha!