Maybe I can address both questions a bit: In a non-capitalist society, individual compensation for labor makes sense as a means of decentralizing and individualizing some aspects of the economy. It also creates some safeguards, in cases where the real difficulties of determining "need" and "ability" might make communist systems of production and consumption at least potentially subject to some forms of exploitation. Different communities are probably going to have different levels of tolerance for disagreements on those matters, and different levels of energy for the sort of constant course-corrections that will be necessary for an economy without individual compensation to function smoothly. Anarchists can probably accommodate individual and local differences in both instances, and that may certainly be more pleasant than all trying to get on the same page about not just the necessities of life, but all of the other sorts of production, distribution and consumption that we can expect to go along with heightened degrees of individual flourishing. We'll grow and be more free together, but it doesn't mean we'll all do it in the same ways. So there may be times when the logical thing to do is to uncouple ourselves from one another economically, so that we can explore individual means of reconnecting through commerce.
All of our labels can be terribly abused, but presumably "mutualism" traces back to Proudhon and the argument behind the claim that "property is theft." The heart of that argument is that no individual should have the privilege of using the fruits of social cooperation to control the lives of other people, and that's true in both economic and political realms. Capitalism is the systematic appropriation of what we do together (Proudhon's "collective force") for the benefit of a few. Governmentalism is the same process ("exploitation") in a different social realm. Some of the things that get called "mutualism" don't pay as much attention to the question of "collective force," but anything worthy of the name ought to start with a rejection of that privilege-to-exploit, and then address the question of how all those social fruits, now expropriated from us by capitalism and governmentalism, might be directed to meet collective needs. And it's only really after that's taken care of, and we have society established on at least a quasi-collective basis, that these questions of individual compensation and individualized consumption can really get free play—and then precisely as a supplement to the sort of economy we are more accustomed to think of in an anarchist society.