I have two questions about the bonus HD:
Bonus HD: Extra eight-sided (d8) Hit Dice, each of which gains a Consitution modifier, as normal. Remember that extra Hit Dice improve the animal companion’s base attack and base save bonuses. An animal companion’s base attack bonus is the same as that of a druid of a level equal to the animal’s HD. An animal companion has good Fortitude and Reflex saves (treat it as a character whose level equals the animal’s HD). An animal companion gains additional skill points and feats for bonus HD as normal for advancing a monster’s Hit Dice.
The Wolf has 2 HD, while my lvl 1 Druid only has 1; the text only says about Extra Hit Dices (I'm pretty sure he means only the extra dices from the animal companion bonus but I'm asking it just to be sure), does that means that I should consider adding the bonus of lvl 2 Druid (+1 BAB, +3 fort) or none at all?
In short, does the animal companion gains any bonus at lvl 1 from having more HD than me?
Considering the text says "An animal companion has good Fortitude and Reflex saves (treat it as a character whose level equals the animal’s HD"; When he says "treat it" he means "to substitue it" or "add it"? The Wolf has better saves than my Druid, if I were to substitute the saves it would nerf him.