There is very little to no documentation on the default aircraft. Historically, X-Plane has had a very steep learning curve because it has expected its users to either know how to fly, or be willing to do a lot of research and learning on their own. This is something we hope to change in the future.
The manual uses the C172 extensively as its example plane. Otherwise, your best bet for POHs will be searching online.
P.S. The yoke cannot be hidden in the C172. I think the Baron is the only default plane with that feature and it is a toggle switch on the left side of the cockpit.