The challenge here appears to be that TimeMachine doesn't support encrypting backups in a native fashion if the backup destination is across a network connection, and TimeMachine fails miserably over WiFi. Can't tell you how many hours of research & real-world experience I've been through to learn that.
So I'm about to download Carbon Copy Cloner to see if it can work across a WiFi connection.
But first, a question: If I have FileVault enabled on the Macintosh HD and I run a backup of that hard drive, does that backup retain any FileVault encryption? Is the backup encrypted and how do I tell? Thanks!