Dwarfurious: Before i continue in the game, i need to know this... Can i just leave the starting friendly NPC behind forever, if so what happens?
Yes, you can; either through the dialogue, or by clicking on his portrait and asking him to "wait" afterwards. Like almost all followers, he will remain (or return) to where you found him. While away from you he won't level up; so if you don't take him from the start I wouldn't bother taking him at all.
However, for a first playthrough he's very useful: he heals you, discusses parts of the main quest, and reminds you to take certain actions along the way. It's your call, but given the choice I'd save the solo dumbspeak PC for at least the first replay.