Sounds like you are going in the right direction. That Nginx setup scripts looks OK at a glance.
If you are already using version control, I would suggest avoiding editing files directly on your server. Instead, edit locally, push to Bitbucket and then pull from your server. It sounds tedious but it's pretty fast and ultimately a better procedure. This is where you might consider Fabric. You could very easily set it up to log in to your server and issue the "hg pull; hg update" commands. From your command like you just type "fab production update" where "production" is a description of your production environment and "update" is python function in your fabfile.
