The exposition would be the trickiest thing for any adaptation to handle. I agree that one season-per-book isn't the way to go throughout the series, but the first book is well-suited to a single-season adaptation. After that you could do some combining and reworking. For example, you could have a 10-episode first season adapting the first book and then combine the second and third books into an expanded and reworked 16-episode chunk, divided into two 8-episode seasons. That could either track as basically a season per book, with a lot of expanded material, or you could rework it in more dramatic fashion. You could either then stop at three seasons or go on.
P.S. I'm sorry, I still don't see any major "borrowing" going on.
That's fine. Mileage will vary on these things.