I've had good results with fermentation in a growler. Most often, If I have a extra wort that won't fit a carboy then I put it in a growler and pitch a different yeast, typically a reused yeast, as a opportunity experiment. Its basically a big starter at that point.
You might need a smaller...
Using auto-siphon is your best option to get out of primary.
We've had issues getting the canned pumpkin out of the boil kettle so addition during the Mash or using the hop bag/grain bag seem like best bet for the "never again" batch next year.
For the traditional set-up, I've let the sparge run through the FWH in a hop bag for the duration of the sparge. Temperature depends on what you've mashed in at, if you've done a mash-out etc. I don't think having a precise temperature its critical as long as its a typical mash temp/sparge...
I agree that Saison's are they way to go for high temp fermentation and the style is broad enough to do different things with it. An IPA base with Saison yeast could be interesting.