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 you go between exams is based on how long you can wait before detecting an eye problem that has no symptoms. Your health care provider will recommend earlier and more frequent exams if you have known eye problems or conditions that are known to cause eye problems, such as diabetes or high blood pressure.