QA activities in agile development include regression testing, iteration/release tasks testing, and optional release/demo management and documentation management. Common issues faced by QA teams include lack of time and resources, lack of automation, and lack of integration between QA and development teams. The document recommends implementing a QA process with phases for planning, automated acceptance testing, story testing, regression testing, demos, and retrospectives to help address these issues. Key best practices include automating tests, integrating QA earlier, and increasing collaboration between QA and development teams.