Mick
I see no reason why the dukes of Burgundy would not have heralds - as you say they have a role to play at court, at tournaments and in war. There are illuminations showing such heralds at the Burgundian court I'm sure (but cannot check right now).
It is an interesting question re the Swiss - as most of the army was raised from an urban leadership, I'm unsure. The Schilling Chronicles show clearly messangers, who maybe so, but not a distinctive herald wearingt their lord's coats of arms - I'll search further through images when I can.
Re pages, each 'lance' was suppose to include a page, and so anyone who's status enabled them to contract for a lance, would have a page - some maybe younger teenage nobility, learning their creft, and so these could fight in support of a man at arms in many cases.
Simon.