Does the phrase ‘an incident in the racing area’ in rule 61.1 mean that the requirement to display a red flag applies to a boat that is not racing? Is a boat intending to race, but not yet racing in the defined sense, required to hail and display a protest flag when she wishes to protest?

Yes, except that a flag need not be displayed by a boat of hull length less than 6 metres.

When there is an incident that occurs after a boat’s preparatory signal, as a result of which she does not start, when may she lower her protest flag?

When she takes action to retire, such as by leaving the vicinity of the course.

Given that the preamble to Part 2 prevents a boat that is not racing from being penalized in most instances, what point is there in a boat lodging a protest when she is fouled by another when both are intending to race, but neither is racing?

A boat that is damaged before the preparatory signal may wish to claim redress under rule 62.1(b) in order to get average points for the race she cannot even start. To get redress she must prove that the other boat was required to keep clear. Since a decision to that effect can only safely be made by a protest committee having heard the evidence of all those involved, it is sensible to lodge a protest as well as seeking redress in order for the other boat to be present at the hearing, since the other boat would not be a party to a request for redress on its own.

Given the limitations imposed by the preamble to Part 2, would a protest committee be justified in declining to hear a protest over an incident occurring when neither boat is racing?

No. A protest committee must hear a valid protest. Rule 63.1 says so.