I don't know about the whole "Kono being separated from the team at the beginning of each season" thing. I've heard in the past that Grace Park has wanted out of the show, so each time they pull this, I assume they are writing Kono off.
I've seen rumors online that Grace Park is pregnant, but can't find anything more solid than people playing whisper down the lane. And while the fact that most of the shots of her at the beginning
of the episode were head-and-shoulder shots (except for one long shot which could have used a body double), she didn't look pregnant at the end of the episode when she and Adam are in their (un)safe house.
Was suprised they blew up the Camero - though with the drop in ratings, shift to Friday night they want to save money (or maybe they're now getting product support from Ford (so the Cruze will get blown up next week).
Chevy is still a sponsor; when I watched it OnDemand Saturday morning, right after the Camaro got blown up, they ran some bit about Chevy being the official motor company of Hawaii Five-0,
complete with shots of the Chevy each character usually drives.
Also, they won their time slot, with 9.38 million viewers, and overall were second only to Blue Bloods.
If the ratings remain stable, hopefully Friday night will work out for them and we'll get a fifth season.