I don’t know if I’m going to say something stupid, but it seems to me that by entering the metre via the popover, you can indicate the desired grouping (see below). I’ll leave it to the experienced Doricians to explain how to do this.
About the second point, menu Edit>Notations>Beaming ; your can also see my thread on : https://forums.steinberg.net/t/beaming-in-open-time/940122
