The two Elite should be infantry, both for historical reasons and to take advantage of the national advantages.
The elite should be cavalry in the War of Austrian Succession the Austrian cavalry typically got the better of its Prussian equivalents. This army will be hard to win with something the Austrian generals also experienced. (the seven years war version is a lot better)
A cavalry based army the Elite units should probably be one Infantry and one cavalry though I could not blame a player for taking two cavalry and based on the Guard Infantries performance rating them regular is reasonable from a historic stand point.
British armies can march and shoot or at least that's what we think of them doing as war gamers. I would say two Elite infantry and one Elite Cavalry is the right balance form a historic stand point. Also make sure the Hessian, Brunswickers and Hanoverians are in your army. The Irregulars could be highlanders, or more likely German Jagers. The conscript unit could be dutch in the WAS or simply a newly raised regiment from Britain or Germany