The quests you mention are unfinished and disabled in the stock game. They are finished and working in the mods. Build 12 is the main mod. It contains a lot of improvements over the original game (bugfixes, unfinished code finished and other completely new features) and it is highly recommended getting it. I can think of no reason to not use Build 12. The Post Build 12 mods contain the mods made after Build 12. This modpack also contains a lot of great new stuff, but is still slightly buggy. So if you want to have th most stable game, get Build 12. If you want the most new features, get the Post Build 12 mods too.