Tire / tube changes:
Day 1: major (audible) leak in front tube. Patched the tube.
Day 2: pretty fast leak in rear tube. When I took off the tire, I found quite a collection of small glass and rock bits in there, so I went ahead and changed the tire too, even though there was no evidence the tire was punctured. Partly I had never changed a tire and so wanted to try.
Day 3-5 they seemed to hold up pretty well with just a little topping off now and then.
Today (day 6) the front tire's slow leak was at the point where it needed air every hour or two, so I changed it. The tire too, as this one, like the other, was full of glass bits.
If I were to do this over again one thing I would do differently is to start the trip with new tires.