A Performance Tester focuses on assessing the application's speed, responsiveness, stability under load, etc. These are non-functional aspects. On the other hand, a Functional Tester primarily ensures that the software behaves according to the specified requirements, which includes validating user flows, boundary conditions, and UI consistency.

Risk Mitigation involves taking steps to reduce the adverse effects of risks. In this case, strategies such as redistributing tasks, hiring a temporary resource, or adjusting timelines can be considered to manage the risk of project delays caused by the resignation.

Boundary Value Analysis is a technique where tests are designed around boundary values. Since software often fails at the boundaries, this method is crucial for pinpointing defects that manifest at edge cases, ensuring robustness of the application.

The "Iterative" model in SDLC emphasizes iterative development. With each iteration, development processes go through the software development life cycle phases like planning, requirements, design, implementation, and testing. Feedback loops allow for constant refinement and adjustment based on lessons learned.

In incremental integration testing, as new modules are integrated, tests are "repeated" for the new combined group of modules to ensure that the newly added module integrates properly with the existing system. This ensures that with each addition, the system remains stable and no new issues are introduced due to the integration.

To uphold code quality in Continuous Integration, Static Analysis tools are employed. These tools analyze the source code without executing it, identifying potential issues, code smells, or violations against predefined coding standards, thus ensuring high code quality before merging.

Integration Testing involves validating the interactions between different software modules or systems to ensure they work together as intended. It focuses on identifying issues that can arise when individual units or components are integrated, such as data inconsistencies, communication errors, or function mismatches.

Exploratory Testing is an unscripted approach to software testing where testers rely on their intuition, experience, and creativity to identify defects without predefined test cases. It emphasizes real-time learning, test design, and simultaneous test execution, allowing testers to continuously adapt their testing based on the results.

Stress testing involves deliberately overloading the system beyond its specified limits. The objective is to identify system weak points, ensure it fails gracefully, and understand how it behaves under extreme conditions.

Version Control systems allow multiple developers to work on the same project concurrently. When two developers make changes to the same piece of code, the version control system flags it as a merge conflict. The developers, possibly with the help of a lead or reviewer, will then resolve the conflict, ensuring that the final merged code retains the intended functionality from both changes.