To learn more about what's happening on the International Space Station at any given time, check out NASA's frequently-updated ISS blog or their page about the research and development work happening on ISS.
Depends on your body type and metabolism and your routine. But usually it takes around 3 to 4 weeks for visible results. For me it took me a couple of months to actually see any progress visually.
How long does it take to see results? I've been there! Actually, I am a gym rat like you (workout 5-6X a week) and have actually experienced weight GAIN if you can beleive it! What matters most is not so much what the scale says but how you feel and the subtle difference in the way your clothes fit.