Getting advice in these Forums is very pro-active of you. ;-)
Yes, be sure to use the HDMI ins/outs when you can for the easiest connections. HDMI Cables have really come down in price now. ;-)
To separate your DVD & TV Service(Dish/Cable) to your TV, you may need to get a Receiver unit. Some...
Yeah, dealing with Tech Support is hit and miss. :-)
If your main cables are testing OK, you could do a quick check for a loose or cross connection - something audio in/out possibly?
And yes, Netflix does attach a small white ring label around the DVD center. :-)