French language Q&A Forum

Did some reading and it seems that if you are talking about 'YOUR own family' you use  EN FAMILLE.. if the activity excluded anyone BUT family. If you are talking about someone else's family or using a possessive pronoun (he ate with HIS family=AVEC sa famille/he ate with  the Jones family = avec la famille Jones/I ate with (my)  family= j'ai mange en famille. If this is correct why then did Monsieur Dulac not say "Alors, je vous souhaite un bon weekend avec ta famille". Is it because this interpretation is "a good family weekend"; a compound noun with EN;  rather than "a good weekend with family". Or is my reading /premise wrong?

The test asked non specifically to turn "Elles sont parties avant la fin du film"  into a question. While I know that I can reverse the order of the subject and the conjugated verb, isn't it also ok to use the phrase "est-ce qu' "?
My response "Est-ce qu'elles sont parties avant la fin du film" was marked incorrect and I am unclear why

Sans rien - “without nothing“. In English this would be a double negative and would therefore theoretically mean “with something”.  But in French would we always say “sans rien” or could we also say “avec rien”?