In a few video's I have noticed ships and carts. Has anyone heard anything about the use of said ships and player carts or the idea of player caravan's in ESO

Would be awesome, but no one has mentioned anything official and I find it unlikely considering the direction of the game, at least not at launch.

Any video with a coastline has had a boat in it

http://gotgame.com/2013/06/15/e3-2013-the-elder-scrolls-online/

Plus I've watched a few interviews where the camera flashes by a few large sail boats.

I think that's likely just flavor for the area. Considering there's like, really nowhere to even go on a boat in the Elder Scrolls setting since we are pretty much set only on Tamriel with no other continents in sight, I don't see it likely that there would be any sort of nautical travel system other than maybe fast travel.

Dont think it fits to the game... but Ive suggested Merchants NPC guild to them. Tons of players would love to be merchants I think.

If they kept expanding their NPC guild system... that would mean we all ere badass heroes but we could choose kinda side profession to go with it, mechants, entertainers, thief/assasin, warrior, mage etc etc.. just additional paths to usual crafting. Merchants guild could unlock a NPC vendor for player to use?