The answers to the derivations in Quiz 4 are covered here. The answer to the last question about the inverse rule is covered here. Some motivations for why we are starting out with the rules we have covered so far are here. And finally, the lesson covering biconditional introduction and elimination is here.
Week 6 is going to be spent going over many examples of derivations in SD, including ones from the previous problem set. So be prepared to ask questions about how to complete particular derivations and be able to work through them as much as you can beforehand.