Red 2.2v
Green 3.3v
Blue 3.3vFrom this, I assume that I don't need a resistor on any leg but the Red when powered from a 3.3v system. And on the Red leg, calculated resistance is 55ohms. Is this a safe assumption.
With +3.3v you will probably have problems with the Green and Blue (3.3v) LED's because of their forward voltage drop. +5v sounds like a better choice. In any case you still need one limiting resistor per anode suited to their respective fwd voltages.