Donna,
You have our continued best wishes. It must be so hard to watch your dad go through this.
Impetigo is a contagious skin condition, in your dad's case caused by the staph bacteria. It's more common in children because of the cuts and scrapes they routinely get, but is of course a risk to an adult with a compromised immune system.
Given your dad's low white count, the precautions about flowers and fruit are wise, to avoid potential sources of infection. They probably have him on a
low bacteria diet, also called a
neutropenic diet, for the same reason.
The white cell growth factor is spelled "Neupogen" and is also known as filgrastim. You can read basic information about it
here and more detailed information
here.