Fitness of what? If you mean the genes, then a gene may have more copies made of it if it causes some of its carriers to assist other carriers of the same genes in ways that help them produce, rather than reproducing individually.
Yes, exactly, that is fitness. You have framed this like a counter-argument but then just described fitness.
Yes, exactly, that is fitness. You have framed this like a counter-argument but then just described fitness.