Numbering, Branching, Buttons and Best Practices

This is something that comes up a lot for us, and I'd like to know how other people are handling it, and what a best practice might be.

So there's no auto page numbering in Storyline, I understand why, and I even agree. Some clients however do not. So that puts us in a place where we need to add page numbers to our pages. 1 of 25, 2 of 25 etc. Easy enough to build with slide masters and triggers.  Where it gets interesting though is when you add branching to the equation. Say slide 20 forces the user to click one of 5 buttons.  Each button forces them down a branch to learn more about an individual topic.  The learner must view all of the topics by clicking all of the buttons on the root slide, slide 20.  At the end of each branch, the user is returned to Slide 20 to select the next button.  Slide 20 does not have a player next button, but a continue button appears once each of the 5 topic buttons have been visited.

1. How would you number each of the slides in the branches? Should the numbering stay sequential, i.e. 21, 22, 23 etc?  (This allows the slides to match the menu easily, which is less work, but does it confuse the user? Theoretically, because the user can click any of the topic buttons out of order, the could see slide 28-34 before they see slide 21-27.) or should the branch pages be numbered some other way, and if so how (knowing that the visible numbering must match the menu numbering)

2. Whilst navigating from slide to slide in one of the branches, it's fine to use the next button, but on the last slide of a branch, when you are returning to slide 20, the root slide, is it ok to use the next button, or should one use a manual button that says something like "Return to List"?  This creates a minor issue if you're using player navigation, because you'll have to remove the player next button and add a manual button which changes the look slightly, and the position of the navigation. Not my favorite.