The main purpose of static analysis in software testing is to identify defects in the early stages without having to actually execute the code. This is beneficial as it helps in improving the quality of the code and reduces the cost of fixing defects at later stages.

Stress testing is a dynamic testing technique used to determine how a software system behaves under conditions that are not normal or expected, such as under extreme loads, limited memory, or when subjected to hacking attempts. Its main goal is to ensure the software doesn't crash in suboptimal conditions.

Usability Testing is a type of software testing where the primary focus is to ensure that the application is user-friendly, intuitive, and easy to understand. It ensures that the end-users can efficiently complete their intended tasks without facing unnecessary obstacles or confusions.

The "Exhaustiveness" principle suggests that it's impractical and non-feasible to test all possible combinations and scenarios in a software application due to constraints like time, resources, and the infinite possibilities. Instead, focused and effective testing is carried out based on risk and priority.

Dynamic testing techniques involve the actual execution of the software. It's performed when the code is run, as opposed to static testing which is performed without executing the code. Dynamic testing validates the software system in a runtime environment.

The primary purpose of developing test scripts in automation testing is to enable the execution of tests repeatedly without manual intervention. This ensures consistent test execution, efficient regression testing, and helps in validating application functionality across different test cycles.

Regression testing ensures that previously developed and tested software still works after a change. Given the repeated nature of regression testing, Automated Regression Testing is a suitable approach as it can efficiently handle repetitive test cases.

The "Record and Playback" technique involves recording user actions as they interact with the application. The recorded actions then form a script, which can be played back later. This technique is helpful for novice testers as it requires minimal scripting knowledge but is not always scalable.

The "Defect Age" metric is a measure of the time between when a defect is introduced into the system and when it's discovered and resolved. It provides insight into how quickly a team identifies and addresses defects. MTBF (Mean Time Between Failures) measures the expected time between two successive failures of a system.

Usability testing is geared towards understanding how end-users interact with the software and ensuring a positive user experience. The primary considerations involve the system's ease of use, its consistency in design and functionality, and adherence to user interface design guidelines. UAT, on the other hand, determines if the system meets user needs, while load and compatibility have different focuses.