Max – if the Allied player is forced to lose a unit due to the French occupying one of the supplyline cities (Ghent and Brussels for the British, and Brussels and Liege for the Prussians), they have a choice of which of their units to remove.
Each unit (block) on the strategic map had two, three, or four strength points. Each strength point represented one unit (roughly a division) on the battle tabletop.
Mike – for the OOB I assigned each block a unit designation such as British I Corps Infantry, or Netherlands Cavalry, or French Imperial Guard artillery. So when the unit entered battle, I could consult my OOB list and place the correct units on the table. I created the OOB using Mark Aidken's great Waterloo Companion, an amazing resource.
As for terrain, I was going to roll on a table I made and have the players each place a certain number of terrain pieces, but decided that since I was a neutral judge it would be better for me to just lay out the terrain.
Under less time stress, I would have probably tried to model the terrain of each actual location, but I didn't want to slow down the action by trying to do that.