The dog I train in IPO is companion first, we train in the sport for enjoyment, not so much for podium,regional or national level competition.
He has freedom in the house, with my other dogs and the only time he is crated is on training days(in the vehicle all day long)
Crating AFTER a training session is very important, the dog needs some downtime to process what the session was about. I wouldn't do a whole lot of rewarding play/fetch right after a session if there was important learning or progress going on. End it on a good note, and crate the dog up for quiet time.
I agree with not playing before a training session as well, but as soon as I get my dog out of the crate, we are playing on our way to the field(for obedience).
I cue the dog as I am bringing him out of the crate for what we'll be doing. That way the dog will get into the mode right then and there.
I don't withhold food either. My dog will start barfing bile if he misses meals, so I may give a smaller portion before we leave to track, and he'll get the rest after tracking.