I have the Hero 3 black. I didn't really care for the wi-fi remote, it seemed tempermental. I love the smart phone app, lets you get everything set up soo easy. I've never actually navigated the gopro itself as I bought the touchscreen bacpac but later found out about the app.
THe suction cup mount is great BUT you have to use it on a perfectly smooth surface or it will not grab. I trusted it soo much I mounted my gopro underneat the cover of our discbine for some cool shots cutting hay. (Multiple blades spinning 3000rpm with finger beaters behind them).
The roll bar mount comes in handy as well. THe stick on mounts are handy for frequently used locations.
I can't see the point of mounting it on your helmet for a pull, you will hate it. stick it to the back window or make a mount to come up off the center console or something, or just stick it to the ceiling if you can get it to. The only time I've mounted it on my helmet was when we went to a racing go kart track for my bachelor party (50mph karts). That made a neat video except it didn't record when I started in back (since I was #1 on the pole and started in front for 1st heat). So the only video I had was the heat where I was in front the entire time which wasn't as interesting.
Buy yourself as many extra batteries as you can. Especially when using wifi, it will not record for very long. I try to limit wifi use. Ill turn it on to get it setup but if I can I will turn it off if I plan to record for a long time such as when we were karting. However when I put it on the pulling tractors roll cage I just leave it on so i can start it and stop it from the pits. Everytime I stroll through best buy I grab another one. I wish they made a charger for them seperate from the camera. I think I have 10 now.
Make sure you have a good video card in your computer. None of our computers here could playback all of the footage I made at first which was 1080p/60fps. I dropped it to 720p and they can barely keep up. THey are all a few years old though.
Is it sad that a $400 camera the size of a pack of cigarettes can record better video than the 1080p HD Sony camcorder we got a few years ago for $1600 IIRC.