How likely is it that I will need the game controller?
Depends if you have bootmii installed as IOS or boot2.
If it's IOS then not.
If it's Boot2 then worthwhile, just in case.
Oh and don't install Preloader on 3.4 either or you'll brick. The tutorial states you must update to 4.1, make sure you do that before installing preloader. Loads of people make this mistake.
Not really doing much Wii stuff these days.