Dear Roger
I would recommend the Kronostaf Website. It is evolving as we speak.
Pengle and Hurt are translations from German and alas littered with translation mistakes. They are for a person who has spent years looking at the 7YW and the sources they have used. Biles is based heavily upon Pengle and Hurt so have the same errors.
The 24 page Greenwood and Ball booklets are good for the Austrians (c1970s, Prussians (c1970s) and Russian (new in 2012).
Digby's book is quite good and covers a considerable amount of ground.
Certainly the complexity of the Prussian Army caused me to look at the Musketeer Regiments for one volume before turning to the Fusilier Regiments and the Grenadiers. This I need to get back to and should be out by the Autumn but life, moving, other projects and a new job 300 miles away has halted progress.
If you would like to look at extracts of the 4 books here they are.
Prussian Musketeers of the WAS and 7YW
link
Saxon Army of the WAS and 7YW
link
Austrian 7YW Infantry and Engineers
link
Austrian 7YW Cavalry and Artillery
link
In addition there has been a considerable amount of work on the ordnance of the 7YW by Christian Rogge, Digby Smith and myself published in the Smoothbore Ordnance Journal available from Ken Trotman Publishing.
The most relevant issues are
18th Century Artillery
link
Austrian Artillery – Seven Years War and Napoleonic, SOJ-3
link
18th Century Britsh, French, Prussian and Saxon Artillery SOJ-04
link
Prussian 7YW Artillery, SOJ-06 [Published later this year]
Summerfield (2009) Saxon Artillery 1733-1827, Partizan Press
link
These have supplemented and corrected the errors in DDS (2007) Napoleonic Artillery, Crowood.
Also you should go to Christian Rogge's excellent website on 7YW artillery.
I hope that assists.
Stephen