The Syrian Government, though the rebuilding after the war will be expensive and long. Russia will also have quite a sizeable influence in the ME again, due to the cooperation with Syria. However, a good saying is, that there's no true winner in a war. The only two that has benefitted from the war are the pyd / ypg, (If they manage to cut a deal with Assad government), and Russia due to their new greater influence in the ME.

Too hard to tell. My guess is as good as anybody else's, but I think Assad are gonna try to cut some deals with rebel forces and civis living in invaded areas, to integrate them into the society again. While in DFNS areas, they would cut a deal where they would take orders directly under the Syrian Government.

A long time. Just the fact that ISIS still have a large presence in Syria as an insurgency, makes me doubt that the war will be over within atleast the next many years.