In terms of noise pollution from being on a main drag you have more to worry about from buses and cars coming from the street. If there is a bus stop in front of your building you'll get a shocking amount of noise as the buses stop, lower stairs and I don't know what else to produce so much noise. Also, if you're on a busy street you might want to see if any tour buses go by. When you're on the second floor you're at just the right height for the people on a double-decker to peer into your apartment. (I have been tempted to flash them or yell obscenities, but could never make up my mind about which to do. In middle school we would yell "penis" at tour buses.)
Unless you're buying, if everything else looks good, go for it. All the street noise will soon become background fuzz. It may take a bit, but you'll acclimate pretty quickly. At various times in my life when living near a fire station, I would think nothing of the fact that everyone had to stop talking every time a fire truck screeched past.
In terms of traffic in an office, maybe it depends on what kind of place, but none of it should really matter.