Mmelindor - that post would be brill.
While completely new posts are better, as obviously new things mean more readers who read your blog will come to look at CH and hopefully stay for the other things as well, reposts are absolutely fine, and in fact I think about 50% up to now is reposts (although that number is reducing as we get more posts and writers on board). The main thing though is that it is something that CH readers will like and that it is written well.
With regards to putting things on your blog, it is fine if you want to, but again it is better if you can refrain from putting the full thing up straight away, just to make it worthwhile for your readers to come and have a look at CH.
Am I right in thinking you have a wordpress username? Or am I making that up? Either way, if you let me have your email address or wp username, I can send you an invite to be a registered contributor and so you can get properly credited, have your profile etc. It's also easier to do the whole editing/formatting/approving thingy on the system.