Keven,
Some of those cracks, especially the circular ones, look like compression fractures. Before you paint, make certain you do not have any delamination going on your top deck. If you have cracking like that, I wouldn't be suprised if you have a bit of delamination.
I would suggest filling the cracks with a liquid epoxy and then sanding afterwards. The problem with opening up the cracks with a Dremel is that it will take forever and it doesn't really accomplish anything.
One big issue with the top deck is that any filler or any sanding, is going to reduce the traction pattern. I had some delamination on the top deck on my 1980 H16 and after correcting it with liquid epoxy, all of the traction pattern was filled in. I ended up using a product called Interdeck from Interlux to put traction back on the deck. Basically, it is a polyurathane paint with sand particles mixed in. The stuff worked great and the boat looks fine without the hash mark pattern. I taped the deck and painted 2 coats on. It is going on year 2 and it looks as good as when I first applied it.
