How to select S/PDIF compatible devices?

[Faustino Dina]

Hi,
For connecting a DVD player and other digital sources to the AV Receiver I
should use the S/PDIF interface. But what about the compatibility between
devices? I've read about sampling rates, then when buying I should take care
that the sampling rate the source device is sending is supported by the
receiver? What else should I consider when digitally connecting two devices?
Which is better optical or coaxial S/PDIF ?

Thanks in advance
Faustino