Good. From my experience writing first-draft material, I'd urge not to worry about too long and include stuff. Let the editor shorten it by making cuts as he or she wishes.
Exercises are good. I hope you already have 3 picked out. But if you include more and some aren't used in the main manual the others can go into a "supplemental exercises" PDF file attachment. You never know how useful that might be. Let's write down any ideas for exercises we have.
That magic "deja vu" date, when everybody's recession speed was (once before) just the same as what it is today, I think was around year 3 billion. We could use Jorries "tablemaker" to find out the answer more precisely.