1. If the cloning fails, you will still have your original hard drive that can be used.
2. You would need another (separate) drive for the disc image (hard drive backup). I would say to get an external USB connection drive. You can use it to make full disc image (backups) after you get the SSD going. I wouldn't touch the original hard drive. Leave it as is and if you ever decide to sell it you can reinstall it. I have a 2TB Seagate USB 3.0 drive (purchased at Costco) that I use for backups for my various PC's.
3. You will use the Macrium Bootable "rescue" flash drive to boot and run Macrium to do the clone (or to do the disc image backup if needed). There is no other data on the flash drive, just WinPE (a lite version of Win 10) and Macrium Reflect.
Here is some info on Macrium from the tenforums.com Tutorials. It covers everything except clone.
And something I found on cloning with Macrium (not sure if its the same instructions as I gave you but it has pictures.
If there are more questions, just ask and I'll try to answer them.
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