trusteft: Thank you.
I am not going to take any NPC with me. I don't like them in RPGs.
For some of the NPCs you get xp for adding them to your party, helpful in the early game, but you can always drop them off right after. Or sell them into slavery if you want to play that way. You might acquire one involuntarily that refuses to leave. Actually, there are two, but you'll only get one of them. They die pretty easily, though, and can be sold to slavers. The nicest way to get rid of them is to keep them alive long enough to reach the one person who can remove them from your party, leaving them alive and free but very unhappy.
Sounds like you might plan on playing with a low Charisma. Keep in mind you can permanently lose up to 3 CH over the course of the game, but 2 points are voluntary and all give some advantages in exchange. Dropping to 0 or less won't kill you, and will still be treated as a CH of 1 except when you do something to raise CH.
Oh, one important difference I forgot. The merchants restock at intervals from a couple of days to a week, and will add items they didn't have earlier. With guns and ammo in short supply in the very early stages, that becomes important. Some merchants will get much better items later in the game. Sometimes it's caused by a trigger event, others I believe are intentional to keep players from taking shortcuts. For example, one particular town should have the best Small Guns weapon in the game by the time you get there if you play through following the story line, but not if you make a beeline straight there as soon as you can afford it.