Yes, the spleen is one location for lymphocytes to hang out, as well as lymph nodes and other locations. Memory B cells will retain their immunologic memory so

Yes, the spleen is one location for lymphocytes to hang out, as well as lymph nodes and other locations. Memory B cells will retain their immunologic memory so you can quickly create the antibodies for pathogens after vaccination. I doubt vaccine efficacy would change much as a result.