Opening the bookmarks toolbar takes indeed two clicks now (but you can use the keyboard shortcut CMD + B to open it instantly). Regarding your second point, the double click works great, and the bookmark details overlay appears.
I'm on Ubuntu, if that makes a difference about the double click on the bookmark star so perhaps it's a platform issue. But I was referring to the bookmarks sidebar not toolbar. How do you open the sidebar?
On Windows Ctrl+B opens the bookmark sidebar, and ctrl+shift+b opens the "library" popup with bookmarks selected.
My point is that there used to be a button that you could place in a toolbar and clicking the button would open the bookmarks sidebar. That button is now gone. I'm sure that in time I'll get used to the changes in australis but I think it would have been better if they would have been introduced gradually. As it was introduced, lots of things stopped working at once the way I was used to. For me, this is friction and it's not good.