Does the tank have a filter? Usually smaller tanks like that will have under gravel filters, which are not efficient in the long run. If you don't already have one, I suggest getting a hang on back or internal power filter (if it will fit in your tank). Make sure it doesn't have too much flow. Yes, water quality is aways important. Bettas still breathe with their gills, but they are able to take a breath from the surface if needed. They can still be harmed by ammonia or nitrites in your water, which is why it is important to cycle the tank. Yes, it will cycle.