For gaming, I have found that (some of, or rather, the most important of) the qualities that you are likely to find most important in headphones are:
Soundstage - Open/dynamic cans are by design going to have a more expansive stage, the best analogy I can think of is that even the best closed cans are like watching a movie in 2D but good open cans are like watching a true 3D film in 3D (Avatar?)
Positional Audio - a natural byproduct of the size of the Soundstage, it's like trying to fit x amount of something in y amount of space, the larger y is, the easier it is to identify each individual x, but if y is small every little x will be cramped together and picking one from the crowd nigh impossible
Frequency Response - It's simply the nature of the beast but open/dynamic cans tend to have accurate bass but it is not "crappy Civic + pair of 15" junk subs and 1kW amps + music tastes so bad as to disqualify one's genes from the pool", but some (Grado, followed by AKG) manage to provide impressive bass along with the other pros of the open design. Gaming, though, requires Positional Accuracy, and bass is not directional and tends to drown the rest of the acoustics out (think Beats), you can't tell where footsteps are coming from when there's constant "thud pow wham BLAMMO!" assaulting your ears, if you can hear them at all.
The best way to go (my opinion as a gamer, audio enthusiast, and audio engineer) is a pair of quality open back neutral ("studio/reference") headphones. Assuming you have a quality source (I have owned most sound cards, and the Titanium HD is still the most well rounded), you can alter the frequency response to exaggerate footsteps and other Positional cues while turning down the sounds that muddy them via EQ.
AKG Q701 are my most recommended, most versatile, and all around excellent headphones.
Also..
AKG K712
AKG K701/702
Grado SR225
Audio Technica ATH-AD700/900
Superlux are supposed to be great for the cost.
As for mics, Modmic is good. Blue are excellent.