1. If I download the Centauro add-on, will the new Crusader tanks be available to the British army in the main TOW2 campaign? Or are they unplayable and just for the Italian missions?
Yes (I think Arzock is mistaking)
The balance mod will add the Churchill, Bishop, Stug III F and perhaps the UK Sherman (maybe this one comes with Centauro too) and the 17-pounders AT gun!