Tips for "Hanging out"?

I met this girl at the mall. She was there with her friends and we noticed them looking at us in the food court. My friends and I decided to walk over sit down and talk to them. Long story short I got her number. We've been talking a little bit and we agreed to hangout next week. My buddies and I are going to hang out with her and her friends. My question is what should we do? I was planning on like dinner and a movie or walking around the mall or something like that. Also do I offer to pay for her? It's not a big deal to me, I just don't want to offend her or make her feel uncomfortable.. :/ in general any "hangingout" tips would be helpful.