access bookmarks via keyboard

Good day,

New Mac and Safari user here.

I am wondering if anyone might have an idea as to how to access the Bookmarks menu via keyboard (but not the sidebar). I had discovered Ctrl-F2 + B + down arrow, but I was wondering if there might be something more efficient.

This keyboard shortcut suddenly no longer functions as of this morning as well.

Is this common across Mac platform? That keyboard strokes randomly function? I have also discovered that Cmd-N (within Safari) sometimes opens a new window, but sometimes opens a new tab. How can one be certain that keyboard strokes will perform as expected? Or rather, how can one determine expectations of keystrokes?

Additionally, while within this Bookmark menu, I'm curious as to what the keyboard sequence of selection might be. If I depress "T", for example, I would expect that the first entry starting with T would be selected, which it is -sometimes- but then a second depression of the key would select the next entry starting with T. This is not the case. I would love to discover if there is any manner by which to determine what this sequence may be.

Any information is appreciated.