3yo playin', eh?
I would set my auto ISO to what ever high value I am comfortable with (probably 1200-1600) and try to avoid flash when possible. I would use the continuous high speed at 5 (or8 if you got the vertical grip). I would get the vertical grip ASAP and fill it with something. Eneloops are cheap. EnELs are better.
I would use AF-C focus priority, dynamic area 3D 51 points, focus tracking with short lock-on, battery order MB D10 first, ALWAYS shoot RAW, active D lighting on normal, long exposure NR off, high ISO NR on normal.
Oh, wait, I do have all those settings on for my kiddo.
Good luck and have fun with your camera and your family.
