Screen time on adult profile? Or swap controllers?

So is there any way to see on screen time for adult accounts that are't listed as part of family group

1. No.

2. Controllers aren't attached to profiles. If he has a preference of controller, he would be able to just sign into his own account and use the same controller. But if he were to switch to using his own profile, nothing from your husband's account can be transferred to his account. So he would either need to continue using your husband's account without limits, or start over on his own child account so he can have a time limit.

With Xbox One, there is no 'player 1' or 'player 2' until you start a game and designate each player into a slot. On the home screen, anyone can take control through Kinect's recognition abilities and be the 'dominant' profile, even if controllers are swapped.
As such, the controllers don't indicate those player slots because the controllers can be changed at any time.

I believe that sensor is for some additional controlling such as split screen side swapping and motion "enhancement" but is it 100% essential 100% of the time? If it is, please provide source.

The controller is assigned to the gamer profile when you start the console and sign in. If that controller dies and you grab the other one, the console can't assign it because your profile already has a controller assigned to it. IE: only one controller
can be assigned to each gamer profile at a time. So, your best bet (when a controller should die, that is) just swap the battery packs instead of the controller all together. It saves a bunch of time and you don't have to mess around with controller reassignment.

Another option, if your controller dies mid game, just wire it in until the match is over. Then, you can safely swap controllers or battery packs without killing your K/D... if its FPS your playing, anyway. Hope this helps!