Are USB3.0 drives backward compatible with USB2.0 computers & other devices?

Yes.  USB 3.0 devices are compatible with USB 2.0 ports.  The maximum read/write throughput of USB 3.0 flash drives will be limited to the maximum available bandwidth on your USB 2.0 ports, however they will recognize and function properly in those ports.

Likewise, if you have a computer equipped with USB 3.0 ports and connect a USB 2.0 device, the device will be recognized and operate to the maximum capability of that device when connected to a USB 3.0 port.