Please, stop repeating russian propaganda. They wanted to control and reconquer their former imperial colonies. Their claimed Casus Belli were just lame excuses, not actual reasons.
In practice, light gathering correlates to F-stop quite well on most normal modern lenses, transmission losses are very low. The main exceptions are deliberately apodized lenses, which have considerably transmission losses wide open.
For the rest - yeah, f# is just one of important specifications.
He took 3 photos with different colour filters in succession and captured them on large glass plates. Naive alignment possible before digital technology limited the quality of results, but as original separate negatives survived - it was possible to scan them at high quality and properly align digitally. So now we can see those photos in true colour and high quality.
As one of examples a very vivid photo of Emir of Bukhara taken in 1911:
