According to "Focke-Wulf FW-190, Volume one, by Eddie J. Creek and J. Richard Smith,
The first Focke-Wulf Industrie-Schutzstaffeln (Industry protection squadron or ISS) was formed at Bremen on april 4, 1940 flying FW-187 twin engine fighters.
Leutnant and Staffelfuher Kurt Tank
Unteroffizer and deputy Staffelfuher Kurt Melhorn
Flieger Johann Sander
Flieger Wolfgang Stein
Flieger Ewald Rohlfs
Flieger Ludwig Vogel
Flieger August Linde
They were subsequently disbanded August 23, 1940 then re-established at Bremen on October 15, 1942 flying six FW-190A-4's (Black 1 through 6).
In Early 1943 another ISS was established at Sorau (now Zary, Poland). Ago at Oschersleben and Focke-Wulf Langenhagen also had ISS Staffels.
Other than describing some of the air battles and victories, the volume does not go into that much detail on the ISS squadrons. That's about all I know.
One of the ISS pilots, Kurt Melhorn, downed three fortresses on one mission by frontal attack while flying with the ISS Focke-Wulf Langenhagen. He never returned from that mission.