Time flies!

I can't believe we're already at week 10 of our (official) student teaching! Time flies, and I mean that in terms of the semester but also in terms of a single class period. My 10th graders were reading excerpts from Dante's Inferno this week, and it just seemed like I was running really short on time every day! We did read the text in class, and that was mostly because they already have homework outside of class for their big term paper. The plan was to spend a little over a week on the Inferno unit and now it's going to be almost double that. 

My questions are:
1) When am I the one who is holding up the flow of class and should just back off and stop talking so much?

2) Should I give students (10th graders) historical context first or let them debate about the plot of the text on their own before introducing that material?

3) What are effective ways to check for student understanding of the text? Sometimes when we go over the guided reading sheet as a class I get the feeling that only the top of the class understood what happened in the text. Is this because I'm not giving them enough time to process the information or because they just did not understand the language of the text?

4) How do you decide which units are okay to take longer/bigger tangents on

5) What are your tips/suggestions for pacing during a single lesson?