Thanks - as usual the Flyertalk experts come through! I will consolidate this advice and see what I can come up with (I love the idea of a KitKat tasting center …) I am on NH for all four flights, and will bear that in mind for the advice on terminals, above. Sounds like it could be worth going landside to check out Kombini's time permitting (I have 3+ hours each time, but at Haneda, it's quite early in the morning).

Anyway, many thanks again for the very practical advice.