I'm adding here information I've translated (possibly quite badly, but it shouldn't be too far off) from the
Japanese FFXI wiki website. I didn't want to add these to the English wiki because I can't confirm any of it yet.
Abilities Canter - increased riding duration - Jeuno (curious story)
Gallop - speed up (burst?) - San d’Oria (impatient story)
Burrow “scooping dig” - Bastok (worrysome story)
Bore “poking dig” - Windurst (youthful story)
Auto Regen - Improves the rate of recovery - Aht Urhgan? (happy story)
Personalities (Translated from Japanese! So English version will be different.)
"Very gentle. It's a pleasure helping look after him/her."
"Wild, rough. Possibly suited for the military."
"Good endurance. Possibly looking toward transportation."
"Nervous. Watches surroundings carefully."
"Dreamy disposition. Engrossed in deep reverie."
My guess is that these represent the highest stat for the chocobo.
"pleasure looking after" -> high Affection
"suited for military" -> high Strength
"good endurance" -> high Endurance
"watches surroundings" -> high Discernment
"dreamy" -> high Receptivity
Hunger Levels (again, translated)
1) Considerably hungry
2) Hungry to some degree
3) Somewhat hungry
4) Feeling ok
5) Feeling ok
6) Not very hungry
7) Not hungry
8) Not hungry at all
4 & 5 are not typos. They give the same description. And initial feeding reports back this up.
Affection Levels (translated)
1) Doesn't seem to pay attention at all to you.
2) Seems to pay attention to some degree.
3) Starting to pay a little bit of attention.
4) Beginning to like you somewhat.
5) Beginning to like you!
6) Beginning to like you a considerable amount.
7) Beginning to like you suitably well.
8) Thinks of you as a parent.
Statistic Levels (translated)
1) So slight as to be all but non-existent
2) A little bit
3) A little bit less than standard
4) Standard amount
5) More than standard
6) Considerable amount
7) Suitable amount
8) Highest amount!