Questions about the 4 wheel of the T8 2018

Hello Community, I would like to switch from my Audi A4 2.0 TFSI Quattro (B8) to the current V90 T8. And as a four-wheeler, I have some questions that the dealer did not really answer me: 1) I was assured that the four-wheeler was ALWAYS available, even if I drove the (respectable) 50km electric. 2) The four-wheeler (i.e. the rear axle) always goes with a certain percentage, as would be the case with the T6. 3) I have remember that in the next winder, here in the Allgäu, I simply don’t have a four wheel anymore with full snow cover. I hope that you can refute my concerns and relativize them, because if the four-wheel drive is not permanently possible, I would like to switch to the T6 after all. Greetings