Welcome to the world of fish-keeping! :D
1) How often do you change the water (100%? 50%? I'm not sure how much)
It all depends if you have a filter. (seems like you do based on #2) 50% once a week if you do, and 1 100% and 1 50% if you don't. :D
2) How often do you change the filter?
You don't change it, ever. Unless the media is falling out. (media is the sponge/cartridge) If you do, the bacteria that eat the ammonia will be thrown away with it.
3) and Cycling?
Cycling is the process of making a big enough colony of beneficial bacteria which eat ammonia and nitrite; these are two compounds which hurt your fish, and they actually produce it by making waste. Learn more here
, and here