They are an aspect of an economy, normally a culturally specific aspect. If so, I'd like an example please. That was Richard's point, not mine. I don't happen to think so. Agreed, a truism in fact.
Production is the starting point of any economic assessment.
That is a tautology. What you mean is that no money changes hands and no reciprocal obligation or expectation ensues. Mauss was naive in this respect and knew it, what's more. I don't have the time to go into other developments and formulations of the gift, but Bourdieu is useful here if you want a less naive view of what the gift entails culturally and socially. But we're still talking about isolated moments here, not economies or economic relations.