human biology - Antibody production in secondary immune response

1) The secondary response requires CD4⁺ T cells to activate memory B cells. That first paper actually gives some evidence that some of the rapidity could arise because T cells and memory B cells are in very close proximity to each other in germinal centers.

2) Yes. The affinity of antibodies increases during the initial infection, both through isotype switching and affinity maturation, producing far superior antibodies. Upon reactivation, memory B cells can undergo further somatic hupermutation.