A & C, theoretically you are right ; separation responsibilities will be different depending on whether you fly the ILS under VFR or IFR rules.
Practically, there is no difference once you are established on the ILS.
Both Nantes and Luxembourg are class D airspaces.
Being VFR or IFR on the ILS, you are responsible of your separation from other VFR traffics and you will receive traffic information from the controller.
Being IFR, the controller will ensure separation from other IFR traffics.
Being VFR, you need to care for separation from preceding IFR traffic on the glide and you have priority over subsequent traffic that you cannot see in your back.
Practically, the controller will treat you as IFR and ensure separation with subsequent IFR traffic to avoid unnecessary missed approaches.
Just for the anecdote, I remember having to deviate significantly from assigned altitude in a class D holding because of an NVFR traffic. It was coming from my left but I have only 1 life. IFR pilots still need to look outside, even in a controlled airspace at night.
Last edited by Luc Lion; 28th Feb 2019 at 13:50.