Organic users include users from Bing, yahoo, google, duckduckgo etc. Google Search Console will, of course, only hold data from Google.
Users can be higher than clicks because you are getting organic users from different search engines other than Google.
Clicks can be higher than users because a single user can click your website in the SERP multiple times - each click will be counted, but they will still be counted as a single user.
That's interesting. Have you checked the different Search types in GSC performance report? (web, image, video, news, discovery etc) You might be getting a chunk of your traffic from Google News for example, which wouldn't show on your GSC chart without changing the Search type.
I totally agree with this. GSC is summarized data, not actuals. I don't have any proof, just personal observation.GSC is more like Ahrefs and this kind of software: estimations for things, they basically sum up the total clicks for all searches, which generally is not 100% real (not sure which approach the take to make this up, sometimes I believe they do estimations based on impressions and average CTR for such query, instead of showing the real data.