depending on kernel/vm options... hot adding a new virtual drive can be easier than expanding because it could require a reboot to get the new space "seen".
If you know you can expand without needing a reboot of the VM.. then its really just personal preference.
If you can get power at the end of the driveway...
microwave dish setup to avoid digging/burying cables...
I wonder what the limit on an MOCA adapter is?
Yes it would work.
But if the pi set up ends up being slower than your internet connection then it would be pointless. The pi3 Ethernet port and USB ports share a controller... So max speed you might see would probably be under 500Mbps from the rpi