Does anyone have any tips on how to manage the naval engagements?.
Cross the T. A lot.

Is it possible to capture the famous ships like "The Flying Dutchman" or any other famous pirates etc ?.
It's possible to capture any ship should you do it, I believe ship named are randomized, so you'll be doing some looking around before you get the Dutchman.

What are everyone's naval tactics ?.
Perfect the art of the line of battle. Assign your flagship, or the ship with the most guns, to broadsides exclusively.

Can you set your ships so they only use broadsides when the broadside button is active ?.
I don't understand this question. To fire a broadside, the broadside buttong must be clicked and the cannons must be loaded. If they are not, the AI does it for you, and the broadside button will turn red when your ship is ready to fire a broadside.