Schonefeld is wrong. Metro station Airport is very far from Sheremetevo. Actually this metro station is where the old airport used to be. The closest metro stations are Planernoe or Rechnoy Vokzal on different lines.
Buses and minibuses (marshrutnye) runs frequently to those stations for 30 R just 15 meters from exit of terminal building. Taxi to metro station should be around 300-500 R, but as always depending on the time and your language skills etc it could be even more.
Baggage restrictions in metro is as written above, but most times noone cares. And it is possible to buy extra ticket for your luggage. I have never experienced any problems anyway in my dozens of travels last years.
A standard price level by taxi.is around 40 Euro or 50 US to central Moscow. You get the best price for taxi if you walk through the taxi maffia and head for the bus to the metro...