I stand corrected. Apparently proportional representation only happened in the 1986 elections when Mitterrand made that change for that single election [1]. Amusing reading back on what happened vs. what I heard about from others.

Regarding the 3 candidates in 2nd round - yes that's only possible because France allows 3 & 4 candidates to go into 2nd round if they have over 12.5%. This is usually not the case, so 3-rounds are very limited but as you indicate they do present a plurality win possibility.

[1] https://en.wikipedia.org/wiki/1986_French_legislative_electi...