A:AnswerIt is a TV with a remote. Not possible to have keyboard/mouse. It is not a computer. There are android and ios apps that act as a remote control via wifi. Some have a keyboard capability but I have not found one that works very well.
A:AnswerIf it were me I would try hooking something else up to the tv using the same input that your cable box is hooked up to on the tv (i.e. DVD player, etc) just to see if the sound still goes in and out. If it does I would try exchanging the tv if you like it. If you don't really care for the tv I would return it. I like mine and paid for the geek squad warranty just in case any issues came up after the return period.