One option you might want to turn off is the "ask to connect" if in wifi range. What this does is pick up signals where ever you go and ask if you want to connect. It was okay in the beginning, but it became annoying after a while. If I go someplace that I know has a good free wifi, I will manually connect to it in the settings.
Other than that, once you log into a wifi connection, it will always connect to it. It connects automatically for me at home and at school, and I don't have to do a thing.
You will know when you're on wifi or data by the icon on the top by the time. If you're on data, it will tell you 3g/4g which ever service you have. If you're on wifi, you'll get the 3 little signal lines.