rootsrat

It's just a lot of data for the 32-bit Skyrim engine to load up into the game, that is all.

I think you misunderstood. The OP is not very clear, so you're excused :D
 
I think Halde installed everything via MO, hence they haven't got any mods in SkyrimData folder (correct?).
 
To answer the question - when you will be reinstalling the textures MO will ask you if you want to Overwrite, Merge or Rename. Overwrite will do just that. Merge will overwrite any files with the same filename and add any new files (in this particular case it will be 100% overwrite, as there won't be any new files) and Rename will create a new mod in left hand pane with the new name. 
 
The beauty of MO is that you don't have to worry about overwriting mods, as each mod is stored in a separate folder, and you can modify the installation order in the left hand pane.

Vanilla Skyrim and DLC don't need a specific installation order. They're all getting installed into a single Skyrim folder.

You have to install the mods in the exact same order as they appear in the guide.

See this thread which is now sticked.

The installation order is different to the load order. Install everything as per the guide, and then let BOSS sort the plugins for you.

Make a copy of your /profiles folder too, delete all the profile but the Default and try again - it may be just a corrupted profile that won't load up.