206 1.4 VAN 2005 No information about my model vehicle

Hello,
I just joined the forum and want to get information about the vehicle I use.
I would like to point out that this vehicle is my first vehicle and it has been 2 weeks. I am not considered as well knowledgeable about the vehicles. I do not have any idea. I am also a student at the same time. I bought a Peugeot 206 1.4 VAN 2005 model vehicle.
In short, without further ado;
As soon as I bought my car, I had the maintenance of the car in Korkmaz Peugeot authorized service in Konya and paid a figure like 2350 TL. In general, the car was good walking but they used a little contempt. As such, I had the idea of modifying my little car without a "bum" car.
In my car, I gave the first priority seat covers, floor mats, brake lights, speakers and tape.
I temporarily replaced the car's speakers using 4 speakers and a subwoofer in the 5.1 home theater system. Since my job is during the school season, I have to wait for the salary :)
My tape is the original tape recorder of peugeot. I do not want to spoil the authenticity of the tape, but listening to the radio is not attractive to me.
My question to you is;
How can I add AUX output to my tape (except the cassette adapter)?
Does the three-line display fit my vehicle?
Can I activate the trip computer and the key (do you know, I don't know) on the end of the wiper arm?
Can I apply a cheap method that can close the vehicle windows from the key? If I can, what equipment and how?
Does it make sense to have a matt color coating instead of painting my vehicle due to small stones and washing scratches?
I am thinking of having a compatible speaker installed in the 4 speaker slots built in my car. I want a more original air instead of a pandosite.
The brake lights of my vehicle are working but they are worn out. I will buy the brake light, but I like the new model LEDs. Do you have reasonable prices for this?
I know it's been a lot, but I'm still a beginner in this kind of stuff. I would be very happy if you answer :)
-Note: I will update my questions as I think.

First of all, welcome to Ahmet, we wish you to use the vehicle without any trouble or trouble.