> 7. Just install and use Git??

I made that point generic for a reason. :)

So you git push to your remote, now you (may) have to tell the servers to reload. Along with other things (database migrations if you're using SQL, compiling native code if you have any of that, potentially updating configuration files if your app needs that, updating assets on a CDN/cache etc).

Yes, sure, a post-receive hook can be wired to do these things, but you have to know that and do the wiring.