1. There might be an issue with the backup, but it's probably as good as the data that's running your system now. The controller marked the disk as failing because it either couldn't write to one or more sectors, or couldn't write to one or more sectors. That means probable data loss.
2. Yes, it is possible. Add another disk to the system that is at least as big as the smallest disk in your RAID array. Open Intel Matrix Storage Manager. Right-click on the new disk, and select "rebuild volume."