a) You don't need to update the firmware to play singleplayer and multiplayer on a game. However, online play is unavailable if you don't update. This doesn't matter with games like Smash or Yoshi's Woolly World.
b) Your Wii U can't automatically connect to a free Wi-Fi. You need to set up internet manually at all times.
c) I do not recommend updating. For 4.0.3, the hacks will be easily accessible very soon. They will be performed more easily than on 5.5.x.
d) If you're worried about auto-updating of the console, turn on Tubehax DNS. This will block Nintendo's update servers, causing you to remain on your current firmware.
e) Organize your spelling next time, please.