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.
Timing. Make it a practice to eat large meals at least three to 4 hours before working out. If you have a smaller sized meal, you can work out two to 3 hours after eating. Light snacks are typically fine when eaten right before and even during exercise.