Yes, yes, and no, respectively.
The best racing sailors tend to come out of dinghys rather from heavier boats. It's fun, but is it more difficult as you get older? Yup. Your weight is still equal to the boat's weight (or worse), and it's slower for you to move it around, which latter is critical to boat balance.
Lasers are the bomb. But as I approach 60, I light that fuse less often ;-)
I'm thinking skiing is similar. At 20, you ski the double-diamonds and hit every mogul. At 50, you are satisfied with the single diamonds (steep, but not lumpy). At 60, you cut a few turns, and are happy to arrive back at the base lift.