Will this mod download to the Gog version? Without changing anything else? Will it wipe out the game I am currently playing or effect the expansions?

I'm not aware of any differences in the data files, really the only difference between the GOG version and the original retail version ought to be the absence of a CD check. Every mod, and this includes TR, should work just fine.

Do you think it would wipe my game in progress?

No, it's just a mod. However, you probably will want to use MorrowindCodePatch to change the world map to see it. I think you want to install TR before changing the map because changing the land after will cause the map to be regenerated and you'll lose the places visited marks from before.

One other thing: Make sure that you are actually on land when you save the game before installing the mod.

If you are in the water in a spot where Tamriel Rebuilt adds land to the map, I don't know what will happen. Knowing Bethesda, the game will probably crash or behave strangely, but then again, my "no playable races" mod, which I expected to cause problems, didn't interfere with starting a new game, as I was able to get past race selection.

The game is patched to the last version of Morrowind. There should be no discernible differences between the GOG version and the normal retail (or Steam) versions (outside the Steam one requiring Steam and not coming with the Construction Kit).

That said, modding Morrowind with all the various mods and overhauls out there usually is precarious. Look up some guides on what order to install in. And it's always best to start a new game post-serious-modding, just to ensure the cleanest possible experience.

Zort. It looks like Beyond Ysgramor is incompatible because of New Tear being smack dab in the middle of the mainland. How can I fix this using TES? I basically just need to shove the island to a spot where it's not a problem. I will be skimming my current mods to see which else might conflict, but it looks like Beyond YsGramor is the biggest problem.

There's TESFaith. (Name is a play on "faith moves mountain": TESFaith moves landmass.) However you'll need to do a second pass to compile the scripts, unless you play with OpenMW (which ignores the scripts' compiled bytecode and interprets their source instead). There's the old TESFaith as a command line tool, which requires you writing a cfg file; and TESFaith# with a graphical interface.

http://www.oceanlightwave.com/morrowind/TESfaith-Readme.html
http://timeslip.users.sourceforge.net/morrow.html
http://www.nexusmods.com/morrowind/mods/43577/?

Oooh thanks!

From my quick analysis of my existing mods, it looks like it's only Beyond YsGramor and Lothavor's Legacy that conflict (for the mainland, it looks like GhostPath and Havish will conflict... if I'm really unlucky Suran Underworld as well).

So I'm guessing the TESfaith isn't too difficult to use?

It's relatively simple, but I really recommend reading the readme thoroughly to avoid making mistakes. You'll also need to figure out where you want to move the landmasses; generally straight north should be safe from landmass conflicts with TR.

I kind of wish TR would put some extra space between Vvardenfell and their stuff. Ah well.

I added it ok, but when I water-walked to it near the Black Rose cave. The caves were transparent on the outside. I did not go in. Plus it kept crashing on me I think because of textures. Maybe the load order? I forgot how to have it redo the load order, if that's the problem. Although it did not say that in the errors.

Sounds like a mod conflict. Are there textures floating in the air?
I will say that ever since adding the Morrowind Code Patch, things in MW have been significantly less crashhappy. Back in the day, it would crash on me once every 2 hours minimum, but now it will be about once every 6 hours.

I have the code patch in it now. But I have not gone back yet. Also where was it that you fix the load order?