You should always fight at your near minimum weight. I used to kick box and also trained in ishin ryu ju-jitsu for years and when I first started competing in tournaments I wanted to get bigger/heavier so that I could fight in higher divisions, but my body didn't feel right, and I was slower and not as effective! That's why most fighters drop weight before a fight.
As far as protein is concerned, unless you want to be a body builder like Geo and Dude, then knock yourself out with 2-2.5g/kg, but for conditioning I always went for 0.75-1g/kg of high quality protein but my man source was good food and kept my intake to ~25g per meal/serving.