Can't find an online manual for the medion but what you're trying to do shouldn't be too hard.
First up any reference to red,white & yellow the yellow is video. red and white is audio.
Second HDMI ARC is a feature. You might still be able to plug a HDMI cable between the sound bar and the TV. You may need to set the TV menu to send sound via hdmi.
Third any audio plugs you use you may then need to set the TV audio menu to use them. Check it out.
The 3.5 headphone connection should work. If you're getting static then possibly something is malfunctioning in this area (either TV or Soundbar)
The TV has a SPDIF output. Not sure but this might be the same as optical output?
I think you may have to look at the Television closely, the RCA sockets on your TV are likely to be inputs, not outputs.
I am not at all familiar with your Thomson TV but most of the really cheap units don't have audio out unless you call the 3.5 mm headphone jack audio out. Some equipment allows you to change a setting for the headphone jack to be audio out for that application but not likely for that unit.
It is best to spend a couple hundred more and get a much better TV IMO such as a Full HD popular brand with Toslink or some other audio out.
Personally, I don't care what you or I watch, we alone will not control what is broadcast. You are in the minority.
If American Pickers rated higher than Better Homes and Gardens, they would swap the assigned channels for those programs. If you are in Melbourne or Adelaide you would have to watch it in SD. Other capital cites you have a choice.
Mate, I'd much rather American Pickers than Better Homes and Gardens for example... not sure about you there.
You do realise that 7 will switch the main channel to HD again for the tennis, just like they did with the Olympics right? If it turns out to be on 7Mate only, well it will already be HD.
Personally I rarely watch the main channels now... I prefer ABC2 to ABC, I prefer 7Mate to 7, I prefer 11 instead of 10, etc.
I hope that News24 is somehow kept in 720p HD if they make the main ABC channel HD.
Most of what is on FTA nowadays is utter rubbish... so I spend much more time now watching BD movies and streaming.