The car radio should fit without any problem, as it is a standard 1DIN format. However, given the position of the radio in a Twingo 2, the smartphone holder may limit your access to the heater settings. It's not certain that your smartphone screen will also be visible from this angle.

I'd advise you to go for a standard bluetooth car radio, as the pioneer mobile app provided absolutely nothing extra and restricted the use of basic functions. The positive point was the smartphone holder, which is solid.

Should work without additional material yes.

This should be possible without any problems.