Contrast showers (hot/cold) you can use any day, 3x a day....however it fits in. It's just another way to increase blood flow, increase nutrient delivery to muscles, increase waste removal from cells, and give a boost to the immune system. It doesn't have to be right after a workout to have long term health affects...I use a cold cycle everytime I shower.
As for pwo nutrition that can vary depending on your goals and training. Lots of different opinions...but I will say most probably favor a meal that has healthly protein and healthy carbs is always good. You can decide whether you want to start using protein shakes, amino acid supplements, creatine, etc....so many options, so little time. But you can never go wrong with a good healthy meal.