The new Charger is replacing out the rest of the Crown Vics. You will see them about 50/50 with the 2014/2016 explorers in a year or so.
I apologize for the depressing video, RIP to fallen officer Lucas.. If you watch the procession you'll see that there's almost no CHP vics any more. In the area I live in, I haven't seen a vic in a long time, my nearest CHP office already got a lot of theirs replaced with chargers.
Also, no the Ford explorers are not being replaced at all as far as I'm concerned. Just some quick info for anyone who had that in mind.
one more thing, I'm noticing a large variety in the wig wags for the CHP 2016 FPIU, one in the middle of the video with what appeared to be code 3 light stage had different wig wag very the one near the end. Wonder how that works.
To answer your questions
1. Yes, they are used on patrol currently
2. I wouldn't say it's a better fit for the fleet, I think the FPIU and the Chargers will go together quite well. FPIU are useful because they have lots of storage space in the back which is useful for highway and state duties especially at traffic collision scenes. The chargers are quicker, faster and could be well used in a pursuit environment or for catching speeders(especially in LA). I think this is the reason why they are not planning on replacing the SUV just yet, they both have their strengths and weaknesses. A little bit of both is a perfect medium IMO.