I've had a ton of issues with my battery on my Droid Turbo 2. I would definitely recommend checking out GSam Battery Monitor (https://play.google.com/store/apps/details?id=com.gsamlabs.bbm&hl=en). If you have the technical know-how, I would also highly recommend enabling enhanced stats (http://blogger.gsamlabs.com/2011/11/badass-battery-monitor-users-guide.html#permissions).
I found that when I disabled location history for Google services that my battery jumped from MAYBE 5-6 hours all the way up to 48 hours depending on idle use vs. active use with screen on. Not kidding that it was that dramatic.
Hope this helps.
Try the keyboard Fleksy. Every other keyboard I've used on this phone had lag and was annoying to use because of it. Fleksy for some reason is the only keyboard app that types as smoothly on this phone as an iPhone, in my experience.
https://play.google.com/store/apps/details?id=com.syntellia.fleksy.keyboard
What you are searching for is 'immersive mode'. These apps will disable the keyboard when the buttons are hidden, but you will be able to use it once the buttons are visable again.
https://play.google.com/store/apps/details?id=com.gmd.immersive
https://play.google.com/store/apps/details?id=com.phoenixstudios.aiogestures
>Will marshmellow put the current temp in the notification bar?
No, but plenty of apps will. I suggest Weather Timeline.
>How can I have it go silent at night and turn the volume back up in the morning?
The Moto app has something for this, go check it out. But as always, Tasker will also do that and so, so much more.
>Serious I've been out of the game for so long. What did I miss?
Material design, Google Now being actually good, NFC payments changing completely, and a shit ton of battery/stability/security improvements.