Apple Watch for Family Member Questions

We recently got an Apple Watch SE 2nd Gen (GPS + Cellular) for my son. He doesn't have an iPhone, so we set this up for him using the Family Member functionality. It's largely worked well, but we have two questions we can't seem to find the answer to:

• How do you set up activity tracking? He's tried to use it when riding his bike, and it just doesn't seem to be picking up him activity at all. He got a message while trying to use it that he should put his age and other data in, but there doesn't seem to be a place to do that on the watch, or using my iPhone under the Watch, Health, or Activity apps.
• How can I manage the apps on his watch? There are several he doesn't need, but I can't seem to delete them from the watch itself, or from the Watch app.

Thanks,

Mike