The 2280 slot is for SSD / storage, not memory. Memory is RAM.
I’m presuming you mean SSD / storage.
Yes and no.
Technically yes, but there is no screw mounting point for a 2230 lenght SSD. So you either need an adapter to extend the lenght or you need a hacky solution to hold it down. I think I recall someone saying that the standard SSD adapters which are available might not fit, so you might have to modify one or go more hacky.
Depends on your operating system.
If windows, depends on how technically inclined you are. Normally windows will refuse to install on an usb attached SSD / external device (what an 1TB expansion card is), so you need to use a 3rd party installer to bypass window’s block. Google installing windows to a usb drive.
Linux will install perfectly fine.
Be aware though, externally attached devices / usb SSD is not recommended for your boot drive. USB stablity is not as good as internal drives. Imo, it’s fine for short term. Or long term if you’re willing to accept the potential for errors.