You keep the save games when you uninstall a game. But as far as I know, DLCs and patches are also uninstalled by uninstalling that game.

So even if you reinstall the game by disc, you have also to redownload the DLCs and patches (sometimes Gigabytes of data) that the savegame needs to work properly. There goes the "start playing the games after only a few % has been installed"-option if you want to continue a game instead of starting the game from scratch.

Definitely 2TB.

Whether you prefer digital or physical doesn't matter in terms of HDD space. They take up the same amount of space.

I've got a touch under 500GB left on my 2TB HDD. Got my PS4 in March 2014. So that's with the likes of GTA V, Wicther 3, Bloodborne, Borderlands, Last of Us, Uncharted 4, and other big games like that, a few small digital only games, 5GB of save files, few GB of screenshots and videos.

Definitely 1TB or greater. 500GB fills up so fast now that even on disc games get a full install. I'm just too lazy to swap my 500GB out for a bigger one.

I got a 2 TB and its really great, i haven't deleted a game off the hard drive since 2014 and i still got nearly a terabyte left

2 tb, 500 is not enough and you will have to uninstall some games after a while. Not a big problem but you know, it's better if you don't have to do that.