The series was made in 1995. That was the Year of the Boar. So of course Urii would be the youngest.
Pochiro speaks using archaic language like de gozaru and acts a bit like a feudal samurai; he's a dog, and dogs are as loyal to their masters as feudal samurai were to their lords.
There is a rule that the main character of the story of a Novel World is protected by Princess Aura and Goal. You may think Genon possessing Puss In Boots breaks the rule, but it doesn't. The actual main character of Puss In Boots is the youngest of the dead miller's sons, not Puss himself.
The series ends with Nyanma back to normal as Chocolat, but it's unclear what happened to Chocolat after that. How are the citizens of Mugen going to treat Chocolat after Nyanma tried to sink Mugen into the sea?