Patricia, having another look at the 'Die Gartenwelt' article, the other Lévêque rose that the writer felt had been renamed was "Impératrice Alexandra Feodorowna" which he felt, as far as he could tell, was in fact the Soupert & Notting creation 'Prince Hussein Kamil Pascha'. The Empress Alexandra Feodorowna herself was the wife of the last Russian tsar Nicholas II, and their first child, a daughter born 15 Nov 1895 was titled at birth Grand Duchess Olga. This strongly suggests to me that Lévêque certainly did rename two roses at that time in honour of the Empress Alexandra and her baby daughter (so perhaps not the other Grand Duchess Olga, the Tsar's younger sister).

More importantly, I believe I have solved the parentage dispute:-
In 'Die Rosen-Zeitung' edited by Peter Lambert of Trier (the breeder of KAV) there is an article about the hybridisation of roses written by Walter Easlea (June1902, page 52). He makes a reference to 'Cornelia Koch' and 'Kaiserin Auguste Viktoria' which receives an Editor's remark by Lambert himself which clarifies the parentage. Here is the passage and annotation, plus my translation:

"Von Devoniensis stammen Jean Pernet und Cornelia Koch. Von letzterer Varietät stammt wahrscheinlich, sei es aus Samen oder als Sport, die Kaiserin Auguste Viktoria *).

*) Stimmt nicht; die Eltern waren Coquette de Lyon und Lady M. Fitzwilliam. P. Lambert"

From Devoniensis come Jean Pernet and Cornelia Koch. From the latter, be it from seed or as a sport, apparently comes Kaiserin Auguste Viktoria *).

*) That's not true; the parents were Coquette de Lyon and Lady M. Fitzwilliam. P. Lambert


So, Peter Lambert himself obviously would have known the parentage of his own rose and clearly felt strongly enough about it to correct Easlea's wrong assumption. I assume that by him mentioning the parents in that order means 'Coquette de Lyon' was the seed parent.

Prinz-Heinrich-Mütze means "Prince Heinrich cap", a flat cap which was named after the brother-in-law, Prince Albert Wilhelm Heinrich of Prussia, who was Grand Admiral of the Imperial Navy.
The name of the photographer is not mentioned. The introduction states that the Hybrid Teas and the summer flora was put together from the plantings of the Royal Horticultural School of Dahlem near Steglitz and photographed according to the "Lumière Process".
I found one more photo of KAV in the same book, which shows a shoot from a "German Forcing [nursery]". Will scan and upload tomorrow. The photo shows a small to medium sized bud.