1. It would be too easy to make a dragon the enemy, but Boqin and Da Long had a rather large falling out that led to some changes on the Blue Mountain. It also created some tension in Zhou's journey, and with Xiongmao. As for the secret, erm... I'll have to re-read to remind myself

Also, wrapped in the Boqin/Da Long 'arc' three chapters were deleted from Book 2... and they were the back story to the argument, the main villain and the Wu training... However, they detracted from the story and slowed the pace.
2. With regards to Liu, this is a strange one. Using limited third-person meant that once a character passed out of Haung's and Zhou's field of vision, they were 'off-screen'... which is great, but causes some problems. I have written (or started) a Gang/Liu short story

It was going to be for guns and dragons, but I wrote something else for that! Also, it leaves it open for more, or for readers to wonder what has happened.