Ian, that is one nice looking ship, very neat and sea looks great, nicely done. I found with my PT boat that the practice was relatively stress free......The hard bit is committing to the 'real thing'....lol!
If it helps, take a look at some aerial pictures of KG5. I've seen some models of ships where the spread of the bow waves are far too wide, rather like a too wide arrow head. Try and keep the wave spread a bit tighter to the side of the ship.
Also, at the stern there is usually a flat area of water before the screws start to effect the surface of the sea. Again, have a blimp at some pictures of the battleship.
Just for effect, how about putting a slight lean on the ship and possibly bow down? Might make it look more realistic than sat square and flat.....
From what I can see you don't need any tips on silicone work.....I couldn't anyway, 'cause I'm a newbie too!
Regarding the base, I wouldn't be too concerned about the sea colour....Even the Pacific can be anything from grey to azure blue. I just painted the base various shades of blue, then applied the clear silicone, that way the base colour came through the stuff real nice!
Best of luck.
Ron