In the United States, 208v can be either. It is generally the voltage supplied by a 120/208v 3 phase system. However, using 2 legs of this 3 phase system is called single phase. I won't go into the reasons for that but just understand that 208v can be either single phase or 3 phase.
Yes, but the motor's horsepower rating will not be reached.
No, you will not obtain 230 volts. From a wye connected three phase 480 volt supply, 277 volts can be obtained from one phase leg and the neutral on the wye connection. 480 volts/1.73 (sq. root of 3) = 277 volts.
Only if you want to damage it. "277" Volt 3-phase will usually mean 277 from each phase to neutral, and 480 from phase to phase. By "230 3-phase", you likely mean 120 phase-to-neutral, and 208 phase-to-phase. If you really mean 230, then you are probably NOT talking about a three phase motor.
you need a step up transformer
A 400/230-V three-phase generator hase three line terminals, together with a neutral terminal. The line voltage (i.e. the voltage between any pair of line terminals) is 400 V, while the phase voltage (i.e. the voltage between any line terminal and the neutral terminal) is 230 V.