New
#21
I would start with figuring out what to delete on the H drive. You may have tons of image backups you no longer need and who knows what else. Good free tools are Spacesniffer and CloneSpy, the first one maps your drive visually making it easy to see what is hogging up the space and the second one finds files that have duplicates on the same drive.
An SSD is faster and more reliable. An HDD is a mechanically spinning magnetized platter that is prone to mechanical wear and tear and its speed is proportional to how fast it spins. An SSD has no moving parts so wears out way more slowly and its speed is not dependent on physical movement so its faster. You can use macrium to clone your existing HDD onto an SSD. Imo the only reason not to get an SSD is if you plan to toss your old machine altogether and get a new one.
As to the question of do you need both an SSD and an HDD, it depends on how much backup space you really need. My entire world of computing including backups takes up 100GB out of a single 256GB SSD. I don't technically have a backup drive because I have two identical machines that are clones of each other so they are each other's daily backup. But some people have tons of video, music, or games which takes up TB+ of space. Whatever you decide, you DO want a place for backup that is not your boot drive. Chances are you have way, way more stuff on your H drive than you really need and you can just keep using it that as your backup drive once you trim it down.