About the small black dot:
I had a similar problem with my ipod 4's home button suddenly not working. I opened it up, and removed a mysterious piece of black plastic that was wedged in there. In the process, I accidentally stuck that black dot to my thumb. I attempted to get it back on, and lost it. I was able to fix it with two VERY SMALL pieces of electrical tape( think two corner tips from one piece). I just stuck it on, and the ipod worked fine. In addition to that, the ipod has an electronic home button, activated via settings-general-accessibility-assistive touch. Just turn that on, and a white dot will then take up a corner of the screen. Upon tapping the dot, you are presented with a home button, voice control, and various other options. Hope this helps!