I live in France and my wife is French- thus I might be able to help you with some passage translations.
I will be visiting Lassy, France next week, Aug 31, 2012. It is my first visit, but I plan to do some historical fact digging on the origin of the name.
I don't know my own heritage exactly. But, I've traced very sure lines to James D. (De?) Lacy immigrating into Pennsylvania andmarried to Eunice McCrea listed in the 1850 US census. James Lacy was a professor, land owner/ farmer. He lists himself from Donegal Ireland.
Books I have: 1. The Roll of the House of Lacy, 1928 Pedigrees, military memoirs and synoptical history of the ancient and illustrious family of DE LACY. From the earliest times, in all it's branches, to the present day.Collected and compiled by DE LACY - BELLINGARI
2. The Lacy Family in England and Normandy 1066-1194, Wightman, 1966