Also, is it ideal to do a playthrough without it fiirst or should I jump in with the expansion immediately?

Yes, it is worth it without the expansion - it's a solid game with much fun to be had. Personally I wasn't keen on the changes to the townsfolk (see review by Bluddy on game page) which was why I haven't purchased it but you may find that no problem. Try playing the game for a couple of hours without the expansion and then another couple with and see which you prefer :)