I am really close. I am on Oracle BS installation. When I get to where I choose Vision and Prod - I choose prod but the default is localhost instead of linux. Then the domain is empty. So i manually overwrote the localhost with linus and added server on the domain name. The last box I added /home/Oracle/Prod. Once I press Next .. then it gives me a RW-00000 error. Unable to write to the follwing directory. Please check for permission. So i guess my question - why isnt the linux coming up as default on Host Name when I am choosing PROD.

This error is usually attributed to the wrong host name settings.
When installing linux which host name did your provide? linux.server or localhost.localdomain? If you did not provide linux.server as host name and domain name than you need to fix that first.
Permission error is most likely related to the above as well.

Alternatively you can proceed your installation with localhost.localserver. Just used these instead of linux.server everywhere (including URL and host files and all the coming steps). Up to you.