His best bet would be the 27th of January, 1889, actually, when he got elected a Member in Paris and the mob wanted him to march on the Elysee. The gov't basically admitted after the fact that if he had tried to become President-for-Life or the like there was nothing they could have done to stop him.
Exactly. Had he shown some political savy at that moment he would have become dictator of France, a mix of Petain and DeGaulle with a sprinke of a republican Napoleon III two generations in advance.
He ended up spending the evening with his mistress, which probably explains a bit about why he wouldn't have been a good dictator.
Yep on the long term, having seized power as the incarnation of French revanchist expansionism, he would have ended up just like Napoleon III, crippled his country by leading her to reckless wars and biting more than he could chew. On the brief term, he just needed a bit more common sense on that specific day, a typical PoD.
A Boulanger Presidency? God knows, although probably a sharp swerve to the right.
Yep, like Petain he would have reunified the three wings of the French right, the extreme republicans, the bonapartists and the legitimists under his leadership and built a power base with the Catholics and the Army.
I don't think he would have started a war with Germany, at least not yet; he was a general and understood France's position without allies was pretty weak. Ironically, as a crazy nationalist he might piss off his potential allies, Britain especially (see, Fashoda).
He was not such a
good general and was a braggart nationalist, so he would wait until he has solidified the strategic alliance with Russia in the early '90s, rearming and making loud revanchist claims up to then. He will most surely alienate Italy to stay loyal to the Triple Alliance (his Catholic power base will require a popist, anti-Italian stance), and most likely, having a nationalist political agenda, he will take an intransigent stance at incidents like Fashoda. He might cultivate an alliance with Spain, too, on a conservative Latin-Catholic bloc agenda.
Most likely scenario: WWI occurs half a generation in advance, quite probably over Fashoda, and it sees a Franco-Russian-Spanish Entente vs. a British-German-Italian-Austrian Alliance. Turkey a wild card, the USA might join the alliance as the American-Spanish conflict becomes a part of WWI.
That's another TL I hope to write, sooner or later.