It would be possible to operate the monitor e.g. with Windows at 60Hz or higher, perhaps the setting is still set to 30 Hz? If, for example, Windows only recognises the screen at 30 Hz, then it would probably be due to the cable used or the PC or notebook, there are CPUs with onboard graphics that can only reproduce such high resolutions or even higher (e.g. 4K UHD) via HDMI 1.4 at 30 Hz. In this case, the DisplayPort connection would help, because it also has a higher refresh rate at higher resolutions.
I have kept mine and am happy with it. The curvature takes some getting used to at first because it is quite strong, but now I can't imagine it any other way :)
Can't answer the question 100%, I connected the monitor via docking station via USB-C to Displayport and so the USB HUB only works via USB-B. I think it is really only a built-in HUB.