1) Can you add to your favourites from the Roku's interface? Like say if you are browsing internet radio using the remote and you select a station to play - can you add this to your favourites?
That's simple: After having browsed to a station, instead of pressing "Play" just press "Select", press "Up" to go to "Add to My Favorites" and press "Select/".
2) If power supply is lost for a few minutes, then is restored (like for example during a power blackout), do the alarm/clock settings get lost?
The Soundbridge's clock is receiving the date and time from the configured time server every time it is powered on, so no problems with a power blackout. As I don't have a Soundbridge Radio I don't know if the alarm settings will be lost, but would speculate that they will "survive" a power loss as they should be stored in the non-volatile flash memory.
Greetings from Germany