To me the frame looks more like a 58-59cm. But measure and find out for yourself. At 5' 10" I'd expect it to fit you well. It is definitely not too small for you.

Never heard DT shifters called suicide shifters before. IMHO, stem shifters would be a hideous travesty on this bike but it's yours to do as you please. Personally I would get bar-end shifters instead. More convenient in my experience and not associated with the bottom barrel bikes.