Choosing a mobile app development vendor offering end-to-end services is crucial because it ensures seamless coordination throughout the development lifecycle, leading to a well-integrated, high-quality app. This approach minimizes communication gaps, streamlines decision-making, and ultimately results in a more efficient and successful app development process.

To ensure mobile app's security, follow best practices such as conducting regular security audits and penetration testing, keeping all software components updated, implementing robust encryption and authentication mechanisms, and educating your development team about secure coding practices. Additionally, consider leveraging reputable security libraries and frameworks, and closely monitor your app for any unusual activity or vulnerabilities that may arise over time.

Native mobile development refers to creating mobile applications specifically for a single platform (e.g., iOS or Android) using platform-specific programming languages and tools, ensuring optimal performance and access to device-specific features. On the other hand, cross-platform mobile development involves building applications that can run on multiple platforms using a single codebase. The choice depends on your project's specific requirements and goals. 

To choose mobile development technologies, companies should consider the target platforms (iOS, Android, cross-platform), the project's scope and complexity, the team's expertise, and the desired app performance and user experience. They should evaluate factors such as development language, framework, third-party library support, community and documentation, and the app's long-term maintenance requirements.