For the first question, you would need a rewrite plugin, as WordPress wouldn’t be able to handle the numbers in that string otherwise (it would see every site as a 404 Not Found), as slugs can’t contain slashes of any kind.
Ideally I think your best approach would be to set the post names without the digits (to make them human readable), and then use a plugin such as the Redirection plugin to forward requests to the old URL (with numbers) to the new one (you can set up a regex redirection here, so a simple rule to strip out just the numbers, or you can do one redirection per URL if you want to be extremely thorough).
As for the permanent 301 redirect for removing the blog sub domain, the plugin mentioned above can handle this as well. Manually editing the .htaccess file isn’t advised as plugins or themes may issue a hard refresh which overwrites the content of that file.