Samana is beautiful. I am living in Cabarete, DR right now and I was in Samana just a few days ago. Dont worry about anything, you will be fine. Cabs and moto tasi's are always aggressive here on the island, all you have to do is kindly say no and most of them will go away.
Ideas for Samana; Playa Rincon which is actually a ways a away but it is the most beautiful beach on the island and they serve fresh fish all over the beach, delicious!
If you want to stay near the ship, go on to Cayo Leventado (Bacardi island) which is about a 10 minute ferry ride from the pier. All costs are negotiable, and will probably be more with a ship in town.
they have very very inexpensive group excursions to Playa Rincon.
another good place to look for more samana based stuff is www.samanaonline.com
email me if you have any specific questions or PM me, even better.