Future updates of Sims 4 + preservation of saved Sims?

Heya.

So, my history of Sims is pretty clear. Sims: The Urbz (on PS2), Sims 2 (on mobile) and now Sims 4 (on PC). I'm no specialist on how Origin actually works I actually made account in there only for Sims, so uh.

I've heard there were expansion packs for Sims 1, Sims 2, Sims 3 and probably will be for Sims 4. So, I've got some questions.

1.  When new packs will be available, (bought and) installed, will I still be able to use same Sims-couple with exactly same relations? I've heard about Sims: Supernatural, where you create new Sims, would my 2 Sims be able to survive through update?
2.  Using Origin. Is there way to save or rather copy Sims? I'm moving a lot, a lot of reinstall, a lot of formatting, a lot of crashes (maybe not a lot of this one). Is there a way to copy Sims, house, relations and other data into USB, so that next step would be just copying them back on newly installed Sims 4. Or it's happening somewhere in Origin, so that my data are safe somewhere there online in cloud? I've seen "Gallery" part, you can save your household and house in there. But that's it, no relations, no furniture, no work, no thing (seperately).

Shorter hand: Is there a way to get just 2 Sims, with their relations to one another (married, lovebird, enemies, acqu... acquitance? acquiteanace?... that long word), through every expension pack of Sims 4? Or I can forget about that?

I know that it's unknown to predict Maxis/EA with this. But maybe you've got experience with Sims 2 or 3.