1) LWJGL is usually not a good choice for a beginner (especially if you have no game development experience at all). On the other hand, if you want to handle the tough learning curve of learning LWJGL, then you'll be able to apply what you learned long-term (instead of learning something that you would need to un-learn like starting with Java2D). A good middle-ground might be to start with something like Slick and use that until you are ready to see how it works under-the-hood and then switch to using LWJGL.

2) Yes and no. Textures can be applied to a polygon to make them look like a 2D picture. However, textures can be used for much more - like storing data that can be used during drawing and even 3D textures for other things, so they aren't necessarily images that would make sense to a viewer.

3) Typically, you would want to do that all inside your game (instead of bringing up a new window). Usually you'll have to show some kind of GUI anyways for score, health, etc.

4) You can do that, but a lot of 2D games are just hand-drawn. When just starting out, you might want to consider just getting a simple square or something working first.

5) There are a bunch of tutorials on the web (Google is your friend ).

6) I would suggest starting by making a really simple real-time game. I think my first real-time game was a block shooting lines at falling blocks written in QBasic. That probably dates me a little bit...