On 3rd June 1944 at 1.00 am, after bombing the railway marshalling yards at Trappes, West of Paris, a RAF Halifax bomber (MZ604) was shot down near Longvilliers/Rochefort en Yvelines (15 miles due south of Trappes) by a Me110 night fighter, believed to have been flown by Hptm. Hans Autenrieth out of Coulommieres, East of Paris. The navigator was the sole survivor and he later told me they were suddenly flooded by light from below, which momentarily blinded the pilot, then quickly followed by cannon fire from underneath. That led me to think that a AA battery were using lights only for the nightfighter to come in and use "Schrage-Musik"

I have discovered there was a Luftwaffe anti-aircraft unit operating from the Chateau Porge in Rochefort, now known as the Chateau Rochefort Golf club. The Halifax was hit at 12,000 feet and shortly after exploded. Could anyone please help me with the following:-

1) The identity of the Rochefort flak battery ?
2) Who would have instructed them to use "lights only" ?
3) What constituted Luftwaffe 'light' and 'heavy' anti-aircraft fire ?

Thank you.