Listening to the radio is, in my opinion, a great way to help improve your language abilities. It is a highly effective way to do passive listening. Your brain needs to hear your target language a lot, far more than we imagine. Listening to the radio is one way of allowing your brain exposure to the new language. Even if you don't understand hardly anything you hear, it is still helping your brain get used to hearing the new language.

Yes, it is important practice listen trying to understand what is said. Not only listen for hear.

Yes, if you enjoy it, or at least if you understand enough not to fall asleep. For talk radio, you should probably understand at least 70% to maintain your interest, but for music, 30% might work, since you can enjoy the music even without understanding everything. as "exercise," with an "s," for some crazy reason, is correct, despite the etymology. Note that as usual, we pronounce the single "s" between vowels (even silent vowels) as the "z" in "zebra," that is, with a buzzing sound.

Hi, I've downloaded by Google play an app called Radio France where you can hear a lot of French radio. I often listen it while I'm driving but I still have to decide how usefull it is. For a few minutes I pay attention to what I'm listening to, but I get distracted very soon. Maybe my french is no good enough, so I can't follow as I'd like. I think moovies in french with subtitles in french are very usefull.

It depends on your level. And the program you listen should correspond to your own level: not too high, not to low. So it faut bien choisir l'émission.