Right now I believe the “front page” of the forums can be latest, new, unread, category list.
How hard would it be to create something (theme? plugin?) that offered the list of bookmarked topics on the front page?
I’d love some general ideas/guidance if anyone knows. Thanks.
Look at the Follow plugin. That does almost exactly that in terms of structure.
That said all your bookmarks are already available from the avatar menu?
Awesome, thanks, I’ll check out the plugin.
And yes, bookmarks are still available from the avatar menu, yes. And many (loud) people in my community are confused by that and hate it.
Of course, what’s really happening is this: Discourse is a huge upgrade from what I had before-- my old forum software was written and last updated in 2003, no joke!-- and, to put it simply, the change was too much of a leap forward for many of my current community members.
Will they settle in eventually? Yes, though a few frequent contributors have already given up and left. 
Will more new members (who never grew so accustomed to the old software) be fine with it? Yes.
So I know things will get better… but… this is just where I’m at today with my community 
and they’re already pretty unhappy with all the changes just to get to base Discourse. I keep hearing “Too complicated” “Too many options” “Too much going on” “Too many things to click” …which, compared to the old forum software, is absolutely true.
(There are also other things happening that are also making the community fragile. Some very toxic members were previously allowed to run wild and they aren’t anymore, so those members are griping a LOT and raising a fuss and generally being pretty awful, which we’re managing. But it’s just one more piece of the puzzle that tells me: the simpler and easier I can make the Discourse experience for everyone, right now, is the right way to go for my community.)
Anyhow, we can start a whole 'nother thread about the joys of trying to move an older, entrenched and highly-opinionated community from the stone ages into the future in one fell swoop. 
Let’s just say… the switch isn’t going quite as smoothly as I had hoped, mostly due to human dynamics, but I know we’ll get eventually there.