In Agile development, prototyping often starts with building a "Vertical" prototype. This prototype includes a limited set of key features that provide a deep exploration of specific functionalities. It's not a final or complete product but serves to demonstrate essential aspects of the system.

The Incremental model involves developing a system partially in small, manageable portions. After each increment, further development is determined based on the feedback and the goals achieved in the previous increment. This approach allows for early, partial implementations and continuous refinements.

Typically, developers, who are responsible for writing the code, perform Unit Testing. Developers are intimately familiar with the code they've written, making them well-suited to identify and fix defects at the unit level. While other team members play important roles in software development, Unit Testing is a task that falls within the developer's domain.

The IEEE 1012 standard focuses on verification and validation in the context of system, software, and hardware testing. Implementing this standard involves establishing a comprehensive process, which can be resource-intensive. Challenges include defining test cases, ensuring test coverage, and managing test data. Considerations include the need for proper planning, skilled personnel, and adherence to industry best practices.

Software Quality Assurance (SQA) ensures that the software development process is proceeding correctly by performing activities such as code reviews, ensuring compliance with standards, and verifying that the development process adheres to best practices. Code reviews help identify and rectify issues early in the development process, improving software quality.

When non-compliance with regulatory standards is identified in a software audit, it is crucial to collaborate with the relevant regulatory authorities to understand the specific issues and work on making necessary adjustments to bring the software into compliance. This may involve legal consultations and modifications to the software to meet the required standards. Ignoring or releasing the product as is can lead to legal and reputational risks.

Adherence to the Single Responsibility Principle (SRP) in software design means that each module or class should have a single reason to change. When this principle is followed, it simplifies code, making it easier to understand and maintain. Changes to one responsibility do not affect others, resulting in improved maintainability.

In the Client-Server architecture, services communicate via a well-defined interface using lightweight protocols. This architectural style is characterized by the separation of client and server roles, where clients request services from servers, which can be located on different machines or networks.

The Microservices architecture style provides a structured system that can be decomposed into smaller, reusable modules. In this architecture, the software is organized into small, independent services that communicate through APIs. This approach allows for greater flexibility and scalability in software development.

Adaptive maintenance focuses on making changes to the software to adapt to changes in the operating environment, such as hardware upgrades or new regulations. It ensures the software remains compatible with evolving external factors.