If you currently have vc17 on your bottom, and you're in fresh water, the vc17 should continue to be an excellent choice. Here on Lake Michigan, it's probably the most popular paint. I've used it for many years, and I apply a thin coat every Spring and never get any buildup of paint, and it keeps the bottom clean.
Glad to hear you're thinking of doing the MaineSail program on your topsides. Should look great when you're done.
With regard to your decks, you can use the same wet sand, compound, and polish techniques up there (but not on the non-skid, of course). I did all the cabin-sides, etc., on my Catalina 28 and it looks terrific. It's just harder to do, because there's hardware in the way. Controlling the cord on your grinder/polisher becomes VERY IMPORTANT. It's easier then you may think to have the pad grab you power cord and instantly wrap itself around the tool and your thumb or fingers. For the topsides, 9" pads are good, but on the decks, 4" pads are a lot easier to get into tricky areas.
Once your topsides and non-skid deck areas are done, you can see what'll work for the nonskid. It might just be a very thorough cleaning followed by Woody Wax (not slippery). Or, you might want to consider a product like Kiwi Grip, a paint with texture that's specifically for non-skid areas. It's one-part and cleans up with soap and water.