How can I set a minimum slide view time?

That'd work. But there's another issue [[Warning! TLDR!]]- in my experience you can't force engagement (I've had far more experience USING elearns than I have building them). Either the user is motivated to learn or they're not. Forcing them to spend a minimum of time skimming the content out of sheer boredom through artificially impeding progress will make an already disaffected user either exasperated or furious, while an engaged user won't even notice, because they'll be reading the content.  Unfortunately addressing this is outside of the scope of the designer, as you're dealing with a much bigger issue relating to workplace culture.  It's only my opinion (and maybe I'm just a hippie-throwback), but if you're going into a project with the mindset of designing a learn in such a way as to trap an audience who will, given the option, actively avoid learning, you'll probably produce a much more adversary user experience.  I think sometimes you just need to trust that people will use the tool in the spirit it was intended, because there's a limit to what you can do through design that will actually embed knowledge in an unwilling participant. 

And anyway, to a certain extent it's a self-leveling system.  Those who haven't learned anything fail, either in the broader allegorical sense or in the case of quizzes, literally.

Sorry if this wasn't the place to go into the discussion of the philosophies behind e-learning design, I've done a couple of jobs recently where I've tried (and failed) to convince clients of this same fact, so it's floating right at the top of my mind.

You cannot control when buttons appear on quiz slides, but all you have to do on normal slides is just set the navigation button on the slide to appear at  5 seconds on the slide timeline.