And if there is a max pet level, what is the max level for each stat skill? And do I need to be careful on what I level up?

For instance, if the max pet level is 51, and the max level for each skill is 10, then I wouldn't need to worry. But if the max pet level is 51 and the max skill level is 50, then I would have to be selective on which skills I upgrade since there's an opportunity cost involved. If put 49 levels into crit, and 1 into attack, I could never get that final level into crit since my pet level is already 51 (base 1 + 49 from crit + 1 from atk).