Questions on DNS and YP/NIS together

[Charles Derykus]

I have a few questions regarding using DNS and NIS/YP concurrently:

When must host names be fully qualified in files,  (/etc/netgroup,
/etc/exports, etc.) in order for the two to work together?

I was informed that if any hosts were built into the YP maps, that the
lookup would consult YP, not DNS, for those hosts.  Are there any other
dire consequences than this?  

Are there any other caveats to be heeded?

Any help will be much appreciated.