wow. that's expensive at MB Edmonton. You should get a quote from contact Mercedes St. Catharines
https://www.mercedes-benz-performanc...bout-us/staff/ to get a quote from Justin Davidson, Parts Mgr. See if you can get a discount from him and also see if the price is decent (better than other mb dealers), ask to see if he can ship to you.
As for staggered or square, it comes down to personal preference. If go staggered, then you should be looking at 10 inch width wheel to have a better/proper fitment. If go square, I would go with 265/40/19, with either Conti 860S or Michelin PA5, in which both are very good winter performance tires. (I have Conti 850P which is last year (final year) winter performance tire and 860S is supposed to be better/improvement in dry condition)
Steve