Protein and creatine on rest days

I would like to know if I should drink protein shakes every single day even on days I do not go to the gym, along with mixing in creatine.
I try to go to the gym at least four times a week with a mixture of both cardio and weight training.
Currently, I just have it on days. I go to the gym and have it post workout. I mix that with creatine.I want to gain muscle mass and also lose a little bit of weight especially around the stomach area as I’ve got a bit of a belly.
When I do cardio, I try to do one running session a week around 4 - 5 miles, and 30 minute incline walk or stepping machine.
In regards to my protein intake per day, I’m pretty sure I may just eat enough protein most day and I’m not even sure how to work it out . It might seem a bit of a silly question that because I’m not reaching my protein goal per day that I should definitely have my protein shake every day to help however I’m worried that it may make me gain more weight However I know that the protein shakes will help me reach the daily target for protein
I know that creatine makes the muscles bigger / watery and when you stop, they will shrink in size? Therefore do I take this every day too?
Thanks