I want to purchase the licence but first a question: can I preview my page dev in vertical position of the screen? Ex.: in the Intel XDK preview I can view in landscape or vertical position to see how the site respond.
I would have to think so. What I do is I use Chrome mainly for development. Then I hit F12 for Chrome's Dev tools and then click the second from the left icon at the top to toggle device toolbar. Then in Chrome I can change between media break points easily.
But I would have to assume that if you have a laptop/device that was capable of being tipped on it's side and the windows GUI and the browser adjust accordingly, I wouldn't image there being an issue then. The BSS apps GUI would be a bit narrow I would think but previewing your browser shouldn't any different I would think.