There is no viewfinder, you use the screen on the back, and it's auto focus. We used on vacation in the ocean and on theme park rides and our videos and pictures turned out crystal clear.

Yes Yes and Yes... We used it at the ocean, theme park on rides, fair, even a 6 year old had it strapped to his wrist and it took awesome video. I'd suggest getting a mounting accessory such as the wrist strap which is waterproof and enables hands free recording.

I don't think ours came with a charger, but that was ok because we wanted to buy extra batteries so we got the double battery and double charger combo. However, different box sets may come with different accessories too. Check the included list on whatever set you are looking in to.

The gopro camera is a very FUN thing to have on you anytime you might want picture or video and with the waterproof wrist accessory it is also convenient. Hands free recording. We've used in the ocean, at the theme park, water park, lake, fair and a few other places for both picture and video. And the kids love it too. The wrist accessory goes small enough to put it on a 6 year old's wrist so they could shoot some video.