Can mods be uploaded onto that? 

But glad you told me.  Thank you.  I'm going to start reminding the modders about that (unless they know it already, in which case, excellent).  

I prefer NMM because I suck with computers.  So there!

Can't tell if trolling or really doesn't know what Steam Workshop is.

Just a small point here.   Skyrim has mod managers, yes.   But they were not created or maintained by the producers of Skyrim... They are independent efforts that depend on donations to survive.    Also, for example Nexus, is a far more open and robust vehicle than the Workshop (good and bad points to that) and in turn almost requires the use of other tools like LOOT if one wants to use more than a very few mods together.  The Workshop is fine for casual mod users though, I don't want to give the wrong impression.  One thing one might hope for with it is that with the many updates coming, Workshop entries may be up to date quicker, but I haven't tested that as I have used Nexus far more.   For Civ 5 I only use a few mods and there aren't so many changes so it seems to work fine.  

One thing I am worried about is getting a mod to work and then having a patch and things go wrong - I don't see a way to prevent updates updates completely without disconnecting from the internet.   Seems like you can only delay them until next time you log into Steam.  But maybe I am just reading it wrong.

Yeah, that's what I'm worried about.  Is the Steam workshop capable of maintaining the consistency and capability of NMM? Like Skyrim, this game is probably going to need a bit of user-created mods.  Don't get me wrong: I thought Skyrim was a great game.  But I've never used Steam Workshop before because for the other games the alternatives have consistently been awesome.