Captain America wrote:
Is that about the size of it?

Yes that sounds correct.
Of course you could home-build the interface instead of buying a
commercial product. There are schematics available on the net.
It merely provides some isolation between the transceiver and computer
to avoid nasty groundloops and currents, usually implemented by a couple
of transformers and optocouplers.

Can I send and receive CW using the same process and equipment, with
the appropriate software?

Yes. You may want to check that your interface provides the CW KEY
signal in addition to PTT.