How to field trip abroad??? With parents??!!!

I’m a new teacher (first full year), and another teacher left the school and handed an existing field trip over to me. The field trip is to Spain, and it will be me, 7 students, and 4 of their parents will be joining.

We’re going with a travel group that plans out your tours, hotels, etcetera.

I’ve never done a trip like this before. What do I need to know? How should I set expectations for parents? I’ve gotten a lot of vague advice, but like, do I let the students explore cities on their own, or should I make them stay with me at all times? Should adults be able to take their kids out to their own lunches etc? Should they be able to bring other students? Students are 7-12 grade.

Should I have everyone sign behavior agreements beforehand? If so, what should they say?