Sorry- I don’t see this info in the FAQs: is there a limit to the number of devices that can be used on one account? Can we have it on out Firetv as well as all members of my household (myself, husband, and minor daughter) have the app on their mobile devices?

On the web--the simultaneous login limit is 3. On the apps, there is no limit. In the same household, you could have one person on an iPhone, another person on the Fire TV, another person on their Android, etc.