How to teach first-years?
If you were the professor for the course, I'd give a different answer, but consider the following. 

I'll assume that you have the same group for each meeting, rather than a random selection of students that changes randomly over time. This lets you set expectations and a general flow. 

One problem you may be encountering is that the students haven't yet learned how to learn. They haven't learned how to take notes and study properly. It is a lesson that needs to be taught, actually. Many students at this level have had an easy time of their earlier education. For some, at least, this is now changing and they need better procedures to capture and retain learning. 

If you aren't getting questions, then ask a lot of questions yourself. They can be simple or complex. One of the simplest is to ask the class for volunteers to answer "What was the most important point in the professor's previous lecture?". Ask if anyone has anything to add to that. Evaluate and supplement any answers. 

Use metaphor and examples to explain/illustrate things rather than being pedantic. Try to give them insight. While precision is good, it sometimes masks what is really at the heart of things. Why do some mathematical systems obey the commutative law and others not? 

It takes some experience, but you can turn some things into games. Even competitive games. I once created a Jeopardy like game for teaching key ideas. It was a computer program that automated the questions. "Square Matrices for 10, Professor Buffy". Teams were formed and the students had fun trying to outdo other teams. This might solve your "working together" issue to some extent. 

But just repeating what the professor said isn't likely to be effective. If they don't know what the professor did say then they need some instruction on effective note taking. Also on lecture summarizing, etc. Show them what tricks you used to learn hard stuff. 

In fact, if you want an "ice breaker" question, ask what it was that the professor didn't make clear enough in the previous lecture.