The DoI is out to control Liad completely and totally, and they view Korval as the single biggest deterrent to that goal. For more details on this, your best source would be the Agent of Change sequence. (
Agent of Change,
Conflict of Honors,
Carpe Diem,
Plan B, and
I Dare. )
Dragon Ship definitely ends with me wanting more. (And
Necessity's Child is completely a standalone, not really fitting in any sequence, though the reader for Audible will be the same as the Theo Waitley sequence, I understand.) But I wouldn't hold back waiting, it's too good a book to not read.
I just went through a complete re-read of the entire set of Liaden novels, starting with
Crystal Soldier and reading in chronological order. It was quite enjoyable, and I found lots of little things I'd forgotten or hadn't noticed in my original reading.