The Laws vary significantly on this matter from state to state.
In California this must be disclosed, while in Florida this information in not commonly asked or known.
Exception- if the death was in fact a homicide this information is relevant, and would be disclosed.

Legal requirements to disclose a death vary by state. California actually has a statute regarding this.

Also, if the death may materially affect the value or desirability of the house (e.g., a violent death or if people believe the house to be haunted), it should generally be disclosed. If the buyer asks about deaths on the property (or where an event on the property lead to a death off the property), the seller must disclose.

Just talk to your real estate agent. Often it can just be added as a note on the seller disclosure. Most people will not be bothered by it unless it was particularly gruesome. It is better to disclose than to be sued later for failure to disclose.

I highly doubt it since it has no affect whatsoever on the condition of the home.