Hi Sherril,
So to answer your first question, yes RD&T z/OS and Linux can share the same ethernet adapter, this scenario is described in the zPDT redbook as Scenario 4 in the LANs chapter. As far as being a 10 GB port, I am unsure if this will cause any issues. Some tweaking may have to be done, such as making sure the packet size is not too large.
Regards,
Rick
rbrunkh