Linden, with a slightly larger than 1/3 inch sensor, image quality should be fine for most things that you mentioned as long as you have enough light. A fluid head tripod will allow you to get most of what you need to shoot, the addition of a dolly under it will improve its functionality. For the sprint and shoot or follow the dancing couple situations, a shoulder cam will help but I think that some sort of steady cam setup will do almost as well. If cost is a factor, there are a lot of DIY steady cam solutions (as well as dolly setups) on the internet. Some better than others but all take some practice to achieve good performance. I have made a dolly for my tripod by fashioning a triangle of angle aluminum with three casters that pivot and roll smoothly attached to each of the points of the triangle, and some bungee cords to anchor the tripod feet to it. A very simple 'poor man's steadycam' is an adjustable monopod gripped below the head and the length of extension varied for balance (lots of practice). Keep shooting.