Can I put the chat window on the top of the page, on the side, floating?
All of these options are supported, although different themes support different options. Any of the non-tabbed themes will support being placed in any of the four corners of the page.
For a floating chat window, choose a theme that has pop-out support by finding one whose preview image has an “X”. Then, choose the “Popout Enabled” option at www.olark.com/customize/advanced