I havent got the game yet, but a question on settlements, does it allow me to make a small one room shack for myself without having other NPC's around? I want to just find a spot in the wild and make a small shack for myself and live like a hermit.

In a word: Yes.

There are two prefab shacks, or you can just use the shack foundation and make it neater.

Yep...

https://dl.dropboxusercontent.com/u/87106516/hermit.png

Awesome

You can make a gigantic fortress of solitude, or a small shack. To avoid settlers or npcs coming in, build your home / hermit shack / mega-mall on raise platforms, concrete foundations, or any object that you snap pieces against like stairs.

Add a fast travel mat inside or at upper level somewhere. Remove the raised platforms or foundations or ladders used to snap the other pieces against. You now have a floating fortress only you can get to via fast travelw.

Yeah, there are two small metal ones that are probably more like sheds and a wooden one. There's also some larger prefab huts.

Disclaimer - you can't just build anywhere in the wild. But there are a number of unoccupied settlement areas, so you can build without having any settlers around.

Just not in a wild

You can build only in pre defined locations and most, if not all include some sort of settlement or structure.

Croup Manor and Taffington Boathouse might be up the TC's alley. Or maybe Starlight Drive-In. There are a few places like Nordhagen Beach or Oberland Station that would be ideal if not for the people already living there; does anyone know if we get to use the workshop at settlements if we just kill all of the settlers that live there?

The ultimate in isolation might be Spectacle Island. I've never been there myself, though, and I hear that there's quite a fight involved for anyone that does try to go there.

I wonder what would be involved (from a programming standpoint) to make the entire map "buildable?"

From a programming standpoint, probably not too much. But that would wreak utter havoc on 99% of systems, and the systems that somehow could handle would suddenly discover the true limitations of the game engine the hard way.

What might be okay, though, is a system where we're only allowed to have one little shack at a time to place anywhere outside of the existing sites. I can see a Fallout version of the Frostfall mod taking advantage of the workshop interface for placing down temporary tents and campfires and whatnot.

Interesting. I have yet to do any modding in any Bethesda titles, and the sum total of my modding has been very tiny changes to some support files for Crusader Kings II and Jagged Alliance Back in Action, so not really "modding" so much as "editing." I made quite a few maps for Civilization 3 back in the day and dabbled in a bit of similarly "entry level" modding for that game.

But Civ3 had an "editor" mode that was fantastic.

I would presume that the GECK will allow one to go into a "world builder mode" of some sort so that you can (for example) remove the boarding from the doors and windows of a structure, add floors, stairs, window frames, door frames, doors, junk, furniture, spawn points for mobs? Maybe even quest markers and that sort of thing?

I expect all such things must be doable because they have been done in FO3 as well as Skyrim and Oblivion. But I'm also expecting I need to wait for the GECK to be able to do it efficiently and effectively?

My aspiration is to remove the boarding up of every single building in the Commonwealth, make at least half of them enterable (more if possible), to populate all of the enterable ones with stuff, to assign mobs to perhaps 20%, random spawn points to another 15%, and quest points to 10 or 15% . . . numbers I just pulled out of thin air, I don't really know many structures we are talking about here? 3,000?

What you are talking about is all doable in the editor, yes. It's another task doing that all in-game with the Workshop mode, though, because all of those changes you make to the base world go into your gamesave.

But yeah, the GECK is the same tool Bethesda themselves use to make the entire game and all of the DLCs. You can edit the game-world as much as you please, create new worldspaces, new quests, NPCs, items, whatever. What you're talking about is incredibly ambitious, though. Somewhat like the DCInteriors and NVInteriors mods, but the Fallout 4 edition.

Although you can't build just anywhere, there are some settlement areas that fit the bill. Outpost Zimonja in the far north is a really isolated area that's basically just an outpost designed to be occupied by a couple people. You could build on it and create a big settlement, but it would make a good small one too. You could build a shack there or just use the preexisting structure.

My personal digs is right next to my Armory, and it's the steel prefab that looks like a tiny egg shaped mobile home. Big enough for one guy to live simply.

Don't add water or food and they shouldn't show up. If they do, send them to another settlement. I recommend the Red Rocket on the roof or Greygarden or Finch Farm up on the Interstates above the settlements that are accessable with stairs.