I think you can get from the train station area to that hotel with bus 2, 5 or 17.
If you come from Bucharest by bus it's the same thing, because most buses arrive at the terminal right next to the train station.
Traveling from Sibiu to Brasov is best done by bus (the direct railway between these cities is blocked, trains have to make a detour so they're slower: the trip takes about 2 1/2-3 hours by bus and 4-4 1/2 by train).
Some bus schedules for this route are available on
As for what to see in Sibiu and Brasov check these links: