i can confirm from experience that having them neutered doesnt improve recall - training does that.
As far a humping is concerned cannot really say much on that front cos Taz never did it before he was done (7 months) - he occasionally does it now but that it when he is play dominating Kira. I have been told that it is a learned behaviour, to neutering doesnt necessarily change it - again its training, but you seem to be on top of it anyway.
As for the coat, Taz's doesnt seem much different 3 years on that it did when he was a puppy - his legs have always been fluffy but his torso is quite sleek but i do keep on top of stripping him.
I am sure others will come along with more experience, but having them neutered isnt a magic wand.
Good luck