How to use Lightening Lane with Park Hopper

[A&Amomma]

Hello,

I have a couple questions about using LL. for the first time.

1. How do I use it when I am there for 1 day and have park hopper? Can you book a ride in one park, while in the other one?

2. We are a family of 4. Can I be the only one using the app to get LL for everyone, or does each person need to book themselves?

Thanks