Software quick-fire questions
Do any affordable Thunderbolt SSD cases exist?
Not at the moment. The cheapest costs just under £100, to which you must add the cost of a Thunderbolt cable and possibly an external power supply as well. USB 3 cases for SSDs work out to around a tenth of that total amount, and should achieve almost as good performance.
Does the Magic Keyboard use USB when plugged in?
Yes, when connected using a Lightning to USB cable to a USB port on your Mac, the Magic Keyboard functions as a wired device. It can then be used in situations where a Bluetooth keyboard may not work, such as when starting up your Mac in the Apple Hardware Test or Apple Diagnostics by holding down d when you power on the Mac.