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.
In fact, after one exercise session, you may notice some physical and psychological changes. However, most of the benefits from a routine exercise program will start to appear within four weeks of consistent training.