You will notice that, even when you don't have the urge to go to the washroom, if your penis experiences drastic changes in temperature, you will pee. When you get an erection, your penis gets significantly warmer. Since, with most men, the ability to pee is impossible with erection, you do it after you've orgasmed and have become flaccid. I often have to go to the washroom after I've orgasmed... and i think it's for this reason.
As for the eating... the body goes through some pretty hefty hormonal changes during sexual arousal. The reaction of these chemicals in your body could be causing these cravings. If you find yourself binge eating or something like that after you orgasm, something might be wrong, and you shoudl talk to a doctor or something.
And the whole food tasting different.. I honestly dont' know what could cause this. Again, it could be the hormonal thing.. if it bothers you, you should also talk to the doctor about it, especially if it lasts awhile after you orgasm.