The primary purpose of using software quality metrics in a project is to improve the quality of the software. These metrics help identify issues and areas for improvement, which, in turn, can lead to a higher-quality end product.

Perfective maintenance involves making functional enhancements to the software without disturbing its existing functionalities. It aims to improve the software by adding new features or enhancing existing ones.

The maintenance phase of the SDLC comes after the implementation phase. During maintenance, the software system is updated, improved, and adapted to changing needs and requirements.

The size and complexity of the software are critical factors in determining the cost of software maintenance. Larger and more complex software systems typically require more effort and resources to maintain.

Integration testing primarily focuses on testing the interactions and data communication between different software modules. It ensures that these modules work together as expected when integrated into the system.

In the Waterfall model, testing typically occurs at the end of the development process, making it more sequential. In contrast, Agile incorporates testing throughout the development cycle, ensuring more continuous and iterative testing to catch issues early.

Including SQA processes throughout the software development life cycle is significant because it ensures that quality is maintained at every phase. It helps prevent defects and issues early in the process, saving time and resources in the long run and ultimately improving the final product.

When a software system experiences performance and user satisfaction issues, it's essential to consider performance optimization as a software evolution strategy. This involves identifying bottlenecks and improving system efficiency to enhance performance. A complete rewrite is costly and risky, and patchwork approaches may not address the root issues. Performance optimization is a targeted approach for improvement.

Isolating the unit from the rest of the software system during Unit Testing is essential to identify defects in the unit without interference from other components. It allows testers to focus on the specific unit being tested, making it easier to detect and address issues within that unit. This isolation is crucial for effective Unit Testing.

Portability is the attribute that concerns the ease of transferring a software product from one environment to another, be it different hardware, software, or operating systems. This is important for making software versatile and adaptable.