Living and working in Moscow, I fly SU fairly frequently.

Even when I give them DL number in advance through a travel agency my office uses, it rarely shows up on the reservation, and I have to have them reenter it when I check in. As a ST Elite or Elite Plus, you can check through business class line, which I HIGHLY recommend, and I've always had elite status show up on ticket. Even when I'm only FO or ST Elite, I've frequently had them tag my luggage as priority luggage. I've had no problems with extra free bags even without my medallion card, but it is Russia, and the culture does like paper, so you may want to have your card or a print out ready.