Those are great questions to start with. What is covered? Length of agreement? When something breaks what is the process and fee for someone to come out? What is the cost of the home warranty?
Home warranties can be great & can save some heartache after closing!
I would confirm what the warranty covers (IE does it include your AC unit ) etc, and confirm the cost for a service call. And of course the cost of the actual home warranty!
The basics about what is covered is important. But also speak to your agent or someone who has used the home warranty company several times. Some companies are very good and reasonable while others will come up with every reason they can to avoid making a repair.