It would require someone with knowledge of Blender plugin programming. That would make it much easier :) Unfortunately, so far we do not have resources to hire someone.
I bet it would. But honestly i think it would be much easier than any of the other poll options anyway. And i imagine for people who develop such promising piece of software it wouldn't be that much of an obstacle.
Of course i understand that this is an early development stage and there is still much work to be done, but if you are looking around for more options, you definately should consider blender.
Anyway, here is the proper wiki section
http://wiki.blender.org/index.php/Doc:2.6/Manual/Extensions/Python I know you probably seen this, but it doesn't hurt anyone if i put this here ;)
Btw, is there some sort of a scene format that might be used (like vray's .vrscene) for exporting to a standalone scene for rendering?
And btw2, just as an example (i hope it is ok if i link this) there was a personal project of vray integration with blender
http://vray.cgdo.ru/As you can see it looks really nice (i checked it in very early stage and i can say it worked as expected).
And btw3;) there is a feature for the next release (2.67, with current being 2.66) version called pynodes, that should help with external rendering engines integration.