As for Royal Italien, it is a unusual brown coated unit so it adds a nice contrast to the mass of the French army.
I'm not working to any particular order of battle but I certainly want a number of units to have participated in the classic 4 battles of the WSS, namely Blenheim, Ramilles, Oudenarde and Malplaquet. Saintonge was at all four and Royal Italien at three.
For source material I am mainly working from the Royalfig Gilles Boue set of units; the articles by Mark Allen in Wargames Illustrated; and the new Kronoskaf for the WSS. Backup is various odd book on the period including "from pike to shot"; Funcken; Osprey, etc.