I know it's exciting to have a new camera, and you want to get out and use it, but I suggest you slow right down. The questions you have asked are all very basic things, and with a read of the manual will be answered. You say you don't have time to read the manual, but the time you have spend posting on this thread would have provided most of the answers to your questions. Nikon manuals are laid out pretty much in order of how they expect you to progress, with the basic stuff at the start, and then gradually getting into more deeper stuff.
Things like the scene modes "night" "landscape" etc are all covered very early on in the manual.
Also as you are struggling with the concept of exposure, I suggest you tale the time to learn the relationship between ISO, aperture and shutter speed. The reason you got black shots inside is because you did not set the exposure correctly and the camera was massively under exposing. . For now, don't worry about using manual mode. Use P, or A or one of the scene modes until you get comfortable with setting things your self.
YouTube can also be very usefull. I my self have made detailed videos about the Nikon D3100, covering every single button and setting. I imagine others have made the same for the d7000 so, have a look on there. It's often easier to learn by doing and watching rather than reading.
Just slow down, and be methodical. Rushing will lead to disappointment. You have bought a very powerful and not particularly beginner friendly camera, so there is a very steep learning curve ahead.