You can give CG Textures a try. Their textures are free to use, with a few restrictions (see the license/FAQ).
As for "free" professional game engines, there are a few:
Unity: Free for the basic license, and $1500 for the Pro version. From what I here, it is one of the easiest to use.
UDK: Royalty based license, if you end up selling your game. This is built on the Unreal Engine 3 (used by many developers). It does lack some features from the full UE3 (such as native code, source code, etc.), but is quite full featured. It's interface could use some updating (and they seem to be getting there with UE4 demos, which should eventually make its way to the UDK). There are quite a few tutorials around for it.
CryENGINE 3 SDK: Similar license to the UDK. There isn't as much community support (yet) as Unity or UDK, from what I hear.
There's more out there, but these 3 stick out to me the most.