Do you think the Mane 6 (except for Twilight Sparkle) knew each other before Friendship is Magic, Part 1//2?

Fluttershy and Rainbow Dash knew each other before Twilight Sparkle came to town

Pretty much, yes.

I think they kinda knew each other before, by sight, but not really personally (other than Fluttershy and Rainbow, of course).

They probably had met before, but never really paid much attention to each other...

Depends. If you mean all of them knowing each other, it's debatable. There's absolutely nothing to suggest Rarity or Applejack knew anyone besides Pinkie. Pinkie clearly knew the other four ("I know everypony, and I mean EVERYPONY in Ponyville!"), and Fluttershy and Rainbow's flashbacks both prove they knew each other before Twilight came to town.

Well, Rainbow Dash and Fluttershy knew each other already, and since they all seem to be pretty well-known around Ponyville, I would guess that they would have at least met. Oh, also, they were all in charge of parts of the Summer Sun Celebration, so they probably couldn't have perfectly figured everything out without talking about it. Yeah...

well, Pinkie knows EVERYPONY in ponyville, and AJ and rarity have lived in ponyville for quite a while, so of course they all knew each other. RD and fluttershy obviously knew each other, according to the stories of how they got their cutie marks.

Yeah,but not as best friends. Probably acquaintances.

I think so, because I remember how Pinkie Pie remarked how she was surprised that she didn't know Twilight because she knew everypony in Ponyville.