No experience with Belgian saison but I use French saison quite a bit.
1. Temperature of wort, but the two should be pretty much the same. I am not sure how people are getting big differences between wort and ambient. I run a 1 BBL nano and my 36 gallon batches are 1-3 degrees higher than ambient.
2. You really don't need insanely close temp control if you ferment on the cooler side and make sure temp doesn't fluctuate. The main risk with some yeasts is temperature drops, which can cause the yeast to stall. The basement, first floor, second floor method was all I used as a homebrewer--after experimenting with JC controllers and ferm chambers I decided it was a waste of time, generally.
3. I can't speak on the Belgian or Dupont strains, but with French saison, absolutely not. It will spit out so much fruit flavor it will completely cover up your malt or spices. Do a little searching on the Belgian strain, there are probably some tips.