Larian Studios Forums Divinity - Original Sin Divinity Original Sin - Mods Updating game & Source Difficulty mod versions?

Yes, 1.0.252 is the latest version of the game, and will likely remain so until the upcoming large update (as of mid March, the ETA was "some months").

The saves will be in the same location, unless you create a new profile or switch to a different one.
Each save is a folder in the '..\Documents\Larian Studios\Divinity Original Sin\PlayerProfiles\<ProfileName>\Savegames' folder.

The rest of your description is correct.

You do not need to repack the save. You may want to move or rename the lsv file, though.