I put my whole site in source control I don't store any objects in the file system that is what the CMS is for. Take more backups of your database if you're concerned with losing it. Kentico has built in tools for developers and they work very well.
You might think twice on the development mode your using as well. I highly recommend following Kentico's recommendations and using Portal mode. Your client will gain the most control with that method. And you as the developer will learn how to properly take advantage of all the features (content, development, etc.) that Kentico has to offer. A small amount of time learning up front will make your experience with Kentico 100% better.
Unfortunately far too many developers (IMHO) just jump into "creating pages" and writing code using aspx mode and never learn the other development modes and end up making their life much more difficult than it should be.