Why would one make or buy a 35mm adapter for a camcorder? This allows 35mm lenses to be used (I presume???), but to what end?

Why does the use of 35mm adapter seem to require flipping or rotating the image?

I'm soon to start shooting my first "real" video (scripted, involving my kids/backyard that sort of thing). I'd like to incorporate a smooth moving shot but am uncertain whether I should use my home-built steadycam or build a dolly. The ground where I'd be shooting from is close to a wall and there is the risk of falling into a pond. I think I'd like the smoothness of the dolly and wouldn't mind the challenge of various designs I've seen on line. But is it worth the time and energy for about 15' of track?

Thanks.