Yes; you can do so with .htaccess rewrite rules. modxcms.com/extras does this.
Does Revo support custom routing?
Yes: http://svn.modxcms.com/docs/display/revolution/Content+Types
Does Revo support dropping file extentions?
Yes, TinyMCE (and eventually other RTEs as people develop add-on packages for them) can be integrated.
WYSIWYG integration?
I’m sure this one must have been covered before but I can’t seem to find a reference point... I’ve installed the TinyMCE package and note that there is no HTML link or image manager type integration - is this something slated for the future or am I just not "working" it correctly?
More than likely, yes.
Bug: TinyMCE Package on Update
I’ve noticed that if you simply change the properties of a HTML element via TinyMCE it doesn’t trigger the save button to become active - only adding a new element will cause this. A bug by chance?

If someone can propose one, and it will be flexible to work across any RTE implementation, yes, there is that possibility. We are definitely open to ideas from a UI perspective on that front. The current system needs more work, definitely.
A quick note on the WYSIWYG integration question - I found my mistake, the problem was that to upload files you have to right click within the tree on the left hand side. I found this a little unintuitive, any chance of an "upload" button in future revisions?
They store in the DB. Revo uses xPDO for a DB ORM. All Elements in 2.0.0 are db-based; in 2.1 and further we will introduce file-based Elements as well. For now, you can just use an "include" snippet to do file-based methods (just create a snippet that has one parameter to pass: the filename of a file to include, then include the file in the snippet).
A final question - does Revo store templates / snippets / chunks in the DB or file sytem? From what I can see it seems to be DB orientated, is there a way to use the filesystem without some kind of ugly hack? Does Revo use full seperation of storage from models with mappers or something? Quite happy to build my own if it does.