I am a PHP developer and I probably could find or come up with code. I will tell you a few problems you will find with what you are doing. First, if you aren’t familiar with PHP, you will find it very difficult to modify the WordPress code. It isn’t too difficult, but what you are doing would take some in-depth modification. I don’t know if there is a plugin. Second, you really should show your newest and latest blog posts. Not only does it keep it fresh and new for actual readers, but for SEO purposes as well. Google likes fresh content and spiders your blog more often if it knows your blog is updated often. Just doesn’t make sense to randomize or change the natural order of newly posted blogs.

Hope this helps.