I noticed that the end of my axle/hub cap is missing. now my bearing is exposed. I launched my boat. Do I need to repack my bearing when I get my grease cap replaced. what is that cap called, goes where the bearing buddies goes but it's the cap, what that called?

"Dust cap" or grease cap is what I have always called them. And yes I would repack the bearing just for piece of mind.

doesn't seem like a big deal if its the end cap, should have the zirc fitting for grease gun just inside of it, all seals should be inside of that inner piston...

BEARING PROTECTOR COVERS keep grease off trailer wheels. Fulton Bearing Protectors have an automatic pressure relief feature so the user cannot overfill or over pressurize the hub with grease. When to much grease is added, the excess will escape and can be thrown onto wheels and tires during travel. Bearing covers or 'bras' are used to prevent excess grease splatter. (1 pair per package)

look at bearing buddy on google, this para was from a set of replacement caps