New NAS questions..

Thanks in advance.

1. What brands of USB drives are disallowed for the OS? Two years ago I tried a SanDisk and it didn't work for me.

Will a PNY 32GB Attache 4 USB 2.0 work?

2. Is there and easy way to connect two unraid servers over ethernet to move data fast?

3. Is there any reason 20 Tb WD easystore drives wouldn't be okay?

4. Is there a good way to sync servers over the internet (VPN, rsync, SCP, etc) without endangering security unnecessarily? Or to have a shared directory