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.
Your muscles start tearing down with your very first weight training session, but it could take up to at least four weeks before you can physically start seeing an increase in muscle size. Use the goal tracker on this web site to track your progress.