yoga is fantastic mate, i highly highly recommend it for any athlete or weight trainer.
you will increase your flexibility in all areas, especially helpful for tricky things like your hip flexors. hello increased ROM. (standing, straight legs i can put my palms on the ground cold - not bad at 6'4"!)
ashtanga (ashtanga vinyasa) is the form you want, also known as athletic yoga
especially if you can find an instructor that has grounding in fitness training or physio (you guys call it kinesiology i think). my instructor gears our sessions for maximum athletic benefit and explains the poses and what they hit/help
you WILL work up a decent sweat in an hour session!
in terms of timing, you won't get as much out of a session of ashtanga if you are sore from a 'heavy' day in the gym. conversely weight training right after a yoga session kind of removes the awesome calm feeling and other benefits you get from the session.
i do yoga in the early morning and weight train later in the day
sorry bout the essay, hope that helps!