two suggest

[Enla]

- Plural of Chocobo is already chocobos. I wouldn't mind if they gave it a distinction like how a group of grows is called a 'murder', but thus far they've used the plural form and just calling a group a 'flock' to fairly good affect.
- If he gets any bigger he legitimately won't be able to fit through doors and would be a serious obstruction if he ever reached Yol/Phoneix size WHILE also being twice as long as those mounts. Plus he was regulated to the eight man storyline, meaning he's going to be receiving the Cid treatment from here on out. I doubt Midgardsomr is going to play a huge role in the story for a long time given that.
-It actually doesn't. Primals are summoned via crystals, the energy of which is consumed when the Primal is summoned. If there was excess aether left over the writers wouldn't have made a point on the tragedy of the Ananta giving all their precious crystals away to satisfy a broken woman's desire to keep the reanimated corpse of her daughter functioning. They'd just harness the energy over and over again instead of steadily depleting the crystals that surround their home and engaging in fights - or mining the crystals left by Bahamut's destruction in the case of the Eorzean beast tribes. Relics also don't work like that from what I remember.
There are however theories that the WoL is a primal like construct but that's a debate for another time.