Using Git for web dev on an Ageir server

I am rolling out a new server for the web agency I work for. For years we have been just using two standard dedicated cPanel servers (one for live sites, one for dev sites), with no version control whatsoever. We would start a site on the dev site, when it's done, we would push it to the live site.

So we're finally making a move to a new server, and because we've become a Drupal house, this new server will be run with Ageir. We are also committed to using Features/Context, and likely Deployment to handle moving config out of the DB and into code, and to migrate content content from dev to live or vise versa.

The other piece of this puzzle is using Git. Like I mentioned earlier, we haven't used any sort of source control, and I want to change that. My question is, what do you guys use as your workflow for Git? Do you only repo the sitename.com folders within the sites folder on each platform?

We're new to Git, and version control in general, but here is the workflow we are considering right now.

Ageir runs all of the live sites on it's platforms. We then make a repository for each sitename.com folder on each platform. When we want to dev a site, we fork the repo into a dev branch. From there each developer (There are two of us now) would check out the dev onto their local host, do their work, then commit it back to the dev branch. Once dev work is done, any new content added to the live site is migrated over to the dev version using Deployment, and the dev version is merged into the live or master branch. I'm sorry if I am misusing terminology here, I am new to all of this. Is this the best practice? Is there a better way?

Some questions if this is the best way. When I fork the repo, how does this get setup in terms of being a live working site? Does Git handle this? Does Ageir? Should I also repo the platform? That way I can easily update my localhost with the latest version of the platform?