Is there a workaround to get floating divs in Report Lab?
If you cannot achieve the results you need with xhtml2pdf, I suggest you use ReportLab directly.  ReportLab contains support for RML, ReportLabs own markup language that lets you easily create formatted text, and has a support library called Platypus that makes layout fairly simple using Python objects to represent document parts and page layouts.
The reason you are having problems, by the way, is that xhtml2pdf has to essentially act like a HTML rendering engine that outputs to PDF rather than the screen directly.  As it took a long time and a lot of effort to make good rendering engines for browsers, so, too, does it seem that xhtml2pdf will take a lot of effort to make it of similar quality.  This isn't to say that xhtml2pdf is bad, just that it's going to take time for it to be as good as rendering in a browser, and if PDF output for its own sake is what you really are interested in, I think using ReportLab directly is a better choice.
I generate PDFs with the xhtml2pdf Python package. The output is not optimal. I use floating divs in order to place images and text on the page. In HTML this works but after PDF rendering, images and text ar placed underneath eachother which is not what I want. From surfing the web I learned that the Report Lab package that is used by xhtml2pdf can not handle floating divs. Does a workaround exist? I have tried webkit rendering via QT but the resulting PDFs are of low quality, i.e. character spacing is completely wrong.