Q: Do I need to keep the TC hard wired, or it it possible to use WiFi to connect to the internet and my iMac?

The TC needs to be hard wired to your modem or router.....but it can connect to computers using either wireless or wired connections.

That is correct. In a nutshell, the TC is a wireless router with a built in hard drive.

If you already have a wireless router and don't need the wireless capability, the wireless function on the TC can be turned off, so the device will operate as a network drive for backups.