Hi,
This is a Spad A-series. The two curved bars sustaining the front machine-gun are present on the A2 and A4, but they have no rear-firing gun. So from the descriptions I have, I think that this is the A3, but I have no photographic evidence to confirm this.
Adrien

Maybe? Actually I don’t know where the picture was taken.

Hi,
I would say this is an AEG G.IV in captured markings.
Adrien

Hi,
This is it, over to you!
Adrien

I think that the DH.71 lookalike is the Raab-Katzenstein RK-25, two of which participated in the 1929 European Challenge.
Adrien

That’s it.
Over to you!

Hi Tim,
Is this the Raab-Katzenstein RK-26 Tigerschwalbe ?
Adrien

Near miss: the aircraft shown in the picture belongs to the same family, but was made for high altitude research with a pressurised cabin. It was the first of a series of high-altitude aircraft, which culminated with stratospheric long-range reconnaissance models with defensive armament.
I’ll give the answer tomorrow if there is no taker in the meantime.
Adrien