The iPhone XR is currently the entry-level model from the latest model series September 2018, without dual camera or OLED display. 5G is not yet supported in any iPhone. Maybe the latest models at the end of 2019 but I suspect more likely 2020 models will support it.
Yes, that is so, the eSIM is missing in the description. . I use the XR simultaneously with an eSIM profile from Swisscom and a physical SIM from Swisscom. Works 1A.
The headphone is not part of the purchase you buying a mobile phone not a headphone. The philosophy with the adabter is that you may habe one already it is to waste recources but then again it saves Apple some money too. The world is changing constantly. I had phone for two years and i am absolutely happy.
In principle, this will certainly be the case, but the problem is that the iPhones always come onto the market in autumn (i.e. 6 months from now) https://buyersguide.macrumors.com
due to the corona virus, however, apple has already been hindered in the production of the new iphones, so this year the iphones will definitely come onto the market later. therefore, you can only expect a new device in more than 6 months and whether you want to wait that long?