Hey there pianowelsh,
Re. your question on "scholarly" writings on Franck, can I suggest one written by Charles Tournemire. From memory, it is simply called "César Franck". Tournemire was a student of Franck, and successor to him at the Conservatoire (composition), and as organist at Ste Clotilde. Its probably out of print, but should be in many libraries. Hope this helps!