My DITA to HTML5 plugin makes progress but...

I'm developing an HTML5 plugin for the DITA Open Toolkit. I've managed to get most things working now, especially the new HTML5 tags and a new homepage that isn't based on FRAMESET. Yesterday I got SVG and MathML working. However, I've still got a long way to go, with outstanding issues including :

• Performance issues in the pre-processing stage. Since specializing the DITA OT to include the SVG and MathML domains, performance is rotten. Maps that used to take 3 to 5 seconds to build now take over a minute! To be investigated.
• Images referenced in DITA topics are not getting copied correctly to the HTML5 output folder. This is not a new issue: all existing HTML-based transformations do the same, but I'd like to fix it.
• SVG images in DITA render best in PDF when their width is specified as "13cm" and the height attribute is not given a value. The current HTML5 standard, however, only supports widths in pixels. It's going to be hard to get a single sourcing solution that works for both.
• SVG images appear in the HTML5 output, but there's something up with the fonts. It looks like they're not getting embedded properly, or that the fonts they use need to be declared somewhere in the CSS.
• MathML support in modern browsers (June 2012) is not good. Only Firefox renders them correctly. IE9 and Chrome don't complain about MathML markup, but don't render it correctly.