Use \centering instead of \begin{center}

The center environment adds extra vertical space:

http://tex.stackexchange.com/questions/23650/when-should-we-use-begincenter-instead-of-centering
Use pagestyle{empty} for complete document.

The \thispagestyle{} directive didn't correctly set the page style when
having multiple pages.
Scale both max height and max width

For a discussion how to keep the aspect ratio while specifying max
dimensions for a figure, see:

http://tex.stackexchange.com/questions/47245/set-a-maximum-width-and-height-for-an-image

If running into problems an alternative could be:

    \usepackage[export]{adjustbox}
    \includegraphics[max height=<dim>,max width=<dim>]{file}