Yes. If there is a new version, a prompt will be displayed.
MaxPerforma Optimizer makes a backup of your registry every time you fix errors. They are stored in the "Backup" section. Go to Backup, select a date from which to restore and click on Restore.
Unfortunately some programs consistently create invalid registry entries even if they were previously removed by MaxPerforma Optimizer.
To prevent this you will have to find and uninstall the program that is causing this.
Yes, the software automatically creates backup before every fix.