Note: the game effectively pauses when drawing, and the only limit you have then is how large your ink pot (magic pool) is. Ink is restored quite fast when not drawing, so there's very little reason to upgrade it (unless some later puzzles require more). Of course, being brush heavy in the fighting will make you want to upgrade it. This is also works great for defending yourself when you otherwise feel like you can't (grow trees between the attackers and you, slash at the enemies or the stuff they throw at you, etc.)
Feeding animals gives 1-5 points of praise/adoration (xp) per animal, though single feeding affects the whole herd, flock, or whatever.