Yes. Directional antenna with EXTREMELY low bitrates so that the bits have a long time to accumulate any noise out of the signal. Specifically its at 160 bits per second at a transmit frequency of 8 GHz.
160 bits per second is actually pretty high. As comparison the German radio time signal used by parts of Europe sends out 1 bit per second: https://en.wikipedia.org/wiki/DCF77
Yeah, at the time the probes were launched, 160bps would have been a fairly respectable transmit rate between two computers connected by a cable, located in the same city!
Yes.
Direction + a large enough receiver on Earth. Oh, and lots of error correction.
And we have giant antennas that listen.
Pretty much. The big dish on the voyagers is the comms antenna, not a science instrument.