Thank you for posting your questions.
1) The Deployment Status by Deployment and Deployment Status by Machine reports should show the information you are looking for. If a machine was supposed to reboot and did not reboot yet you would see "pending reboot" as the machine status.
2) Reports work off of the items that you can see in Manage > Items and View > Results including scans and deployments. Therefore, you will need to have deployment results for the machine before you can run a report on the deployments.
3) That is very odd. I would suggest creating a support case for this as logs and certain settings will need to be checked to see if we are not actually sending the information or it is being blocked by something in your environment.
Thanks for the info on questions 1 and 2.
For whatever reason the issue went away between last week and today with sending reports via email.
We are glad to hear that that helped!