Today a Thought Policeman does not need to stare at your telescreen. A computer does that by staring at thousands of telescreens and ignoring everything unimportant. Important events are flagged, automatically recognized, and presented for human review. This way one *can* have 100% surveillance.
With regard to WiFi, I would not be quick to declare victory by not configuring one. First, there may be open networks nearby that the TV may connect on its own. Second, GSM modules are cheap, and if there is sufficient interest such a module can be instructed to transmit over the cell phone network, bypassing your Internet (OnStar works like that.)
An EE or a tech could probably disable all these features by physically removing the camera and the microphone. Covering them up with tape may feel good, but you never know where really those devices are - it may be that you covered up a fake lens.
The absolute best solution is to have no TV at all. Internet is perfectly capable of keeping you informed. I have an old LCD TV, but it is not used, except when relatives come visiting. If you must have a TV, you may want to get a TV tuner, like HDHomeRun, and watch TV on any computer, tablet, or phone in your house. I have one, and it is functional... but not used, as I don't have a need for TV. These tuners are receive-only.
* thanks for the info*