#1 to Dem
IMO, the problem with your image being less than sharp is that you were probably shooting at a very long focal length hand held. Many bridge cameras (including my Canon SX50-HS) have focal lengths that are just about impossible to hand hold despite stabilization. A tripod could help and a monopod correctly used "might" help
As far as a lens for your Sony A7 Mii... I don't think that there is any lens in a decent price range that could capture these two boys from 200 yards distance... The 600mm f/4 costs over three thousand-five hundred U.S. Dollars and still might not be long enough to do the job.
OTOH... some PP sharpening might help this image...
It won't make it a great image but might help a bit...
As far as no sparkles on the water, that is purely a function of the direction and type of available light shining on that water.