It really depends on your type of data, if it's sensitive data or not. And it also depends on what type of backup (Incremental, Decremental, etc.). But you should aim to backup at least once a week, and also do a backup of your original backup.
This type of freedom is called dreaming
Well, you need to partition your hard drive. Partitioning your hard drive designates usable space on your hdd.
And you need to format your hard drive. Formatting installs a file system on to your hard drive, it allows the operating system to read, write and overall understand the data stored on the disk. Without it, an OS cannot keep track of file locations, nor can it typically identify already used sectors (space) on a hdd.
However, neither of these two concepts are tests.
Then there would be no way to see the output based off what you input. =)