There is no specific wireless adapter for Android that can be connected directly to this car radio's USB port. However, the headunit does support Android Auto via a USB cable, allowing for secure and convenient integration of Android functionality into the car. For a wireless connection, external solutions or third-party accessories would have to be considered, but this is not directly supported by the car radio itself.
Yes it is, that's how I installed it. The important thing is to feed the "reversing" signal to the car radio so that it automatically switches to the reversing camera when you put the car in reverse gear. I achieved this by "tapping" the power wire of the reversing light. Hope this helps.
Yes, this car radio fits your car.
It can be optionally connected to the steering wheel via an interface for the steering wheel remote control.
Manufacturer's page with the different interfaces: https://www.pioneer-car.eu/de/de/products/sph-da250dab/parts?brand=Seat&model=Altea&year=2009&category=Multimedia%2520Receivers
The different interfaces on Galaxus:
https://www.galaxus.ch/Comparison/3358224-451173-3358248
I think that for your case, this is the most appropriate: Pioneer Ctsst001
The datasheet should list all compatible models:
https://www.pioneer-car.eu/de/de/products/sph-da250dab
Otherwise, ask your garage or specialist dealer.
The antenna is not included! To use the old antenna you need a special converter. However, it is an advantage to be able to test this, as it is not guaranteed that the reception is really good. I was lucky, the reception on DAB+ is better than on my old device with the special DAB+ antenna, the standard FM reception is not so good. But since Switzerland is very well developed, this will soon no longer be a problem.