1) The document discusses testing throughout the software development life cycle. It describes different software development models like the V-model and iterative models.
2) It explains four common test levels - component, integration, system, and acceptance testing - and their objectives. Component testing verifies individual modules, integration testing tests interfaces, system testing verifies full system requirements, and acceptance testing validates user needs.
3) Agile methodologies like Extreme Programming (XP) emphasize practices like writing tests before code, frequent integration and testing, and customer involvement. Testing is integrated within development cycles under different life cycle models.