|I'm thinking of having an SSD RAID1 setup to eliminate a single drive failure to prevent down time.|
Here's a well-known rule of thumb: if you have important data, either keep three or more copies, or just one. Never keep two, because in case of discrepancies you won't be able to tell which one is correct.
Therefore, you should avoid hardware RAID. Hardware RAID 1 is not reliable in the face of data corruption. It can only protect you against total drive failure. Instead, use a file system that does block-level checksumming and can tell (with a high degree of certainty) whether a block contains correct data. Nowadays, the best option for this because of performance and reliability is ZFS.
|I've read about the issues with backing up to internal drives so I'll have them external and most of the time unplugged and I'll plug them in when I want to perform a backup.|
I've used this method in the past, and I've found that it's actually less reliable than an internal drive. I don't know if it's because of increased wear from start-stop cycles, or because an external drive is more likely to get banged around, or what.
Here's the scheme I would use if I want to be reasonably safe:
1. Working copy in a raidz file system.
2. Frequent backup to a computer in the local network.
3. Less frequent encrypted backup uploaded to some cloud service. If the backup can be made small enough to fit in the free tier, all the better.
4. Occasional backup to an external drive that you keep someplace else (e.g. at work).
|Additionally I think it would make this process so much easier if I were to install a hot swappable bay on the front of the pc and have the system automatically trigger the backup when it detects a drive has been connected to this slot.|
If you want to minimize downtime even in case of drive failure, disk caddies at the front is a must. But keep in mind that with a small setup such as yours, you won't see more than one drive failure every two or three years, tops; with SSDs it depends on how much data you write per day. You'll suffer Internet outages much more frequently. Replacing a failed drive takes only a few minutes. Let's say five minutes per 2.5 years, that's five nines availability.