ReRolled Minecraft Server III

It stands for Feed the Beast, which was originally a challenge map where you started with almost nothing (a lava source block and water source block, and some wood I think), and completed subsequent challenges (like, put 10 diamond blocks in the chest) to unlock more materials that allowed you to make more items and complete more challenges, etc. It made extensive use of all the mods like Redpower, Buildcraft, Forestry, and most importantly Equivalent Exchange, which let you trade one item for another type of item (a bajillion cobble for a diamond for example).

In order to make the challenges equal for everyone, they created their own launcher which ensured people were using the exact same mods. Eventually people cared more about the launcher than the challenges themselves, and now FTB is what I would consider the premiere launcher/mod organizer for Minecraft, much better and easier to use than Tekkit/Technic. It is super easy to add or disable mods that you want to play with, and they have several pre-brewed ones that take literally zero effort on your part to make work. So no more fucking around trying to match versions of mods with each other and finding out halfway through your world that something is hosed.

Unless I was playing vanilla with no mods at all, or server-side only mods like McFly's, I would never play without the FTB launcher handling all that shit for me.

Well it's obviously personal preference; I just find using the FTB pack a lot easier to manipulate, whereas you obviously prefer Tekkit.

I have no idea what Big Dig is, so it might be as awesome as you say it is, but I can't even use all the mods in Direwolf's pack so I'm not sure I need more. From looking at it, it appears that Big Dig has most of the same mods anyway, so you'd probably get about the same experience whichever one you chose. Except that it seems like it doesn't have Redpower (I could see doing without that though), XyCraft (not sure how useful that is yet, but it looks to be awesome eventually), and Thaumcraft, which is the single most awesome mod in existence.

Seriously, if you haven't ever tried Thaumcraft, you're really missing out. All the other mods tend to be more "machine" based, which often takes away from the fantasy aspect of Minecraft, but Thaumcraft is full on magic shit, and it is phenomenal. And the guy that created it is awesome too.

Now we just need to make a set of secret tunnels that go from the different secret rooms we made above the nave to the huge tunnel and somehow get to the wall where Sam and Castor's daughter got through.

You don't need a lot. The tracks are more costly.