1) What have you tried?
2) Doesn't matter, users don't care. What only matters is how comfortable you are with working with a particular one, and how productive you can be.
3) If you think it's too hard, try something else, but base it on your own evaluation of it. Other people will do things differently and have their own reasons for liking certain things.

To be honest with you, I don't think you'll find anything easier than irrlicht when it comes to C++ rendering engines. It doesn't have the most cutting edge technologies or the best design, but it's very simple to get up and running. The tutorials provided on the irrlicht website explain all the concepts you need to work with irrlicht, so make sure you've followed them and that you understand them.

That said, maybe you should start out with something a little more basic so you can get familiar with rendering concepts, as your first question pretty much tells me that you aren't yet familiar with some basic concepts. After that you can look into animation and character controllers and such to get an actual controllable character.