Advanced AI Programming Challenge: Creating a Virtual Assistant

Develop a comprehensive outline for designing and implementing a virtual assistant using AI technology. Include details on the primary functionalities it should offer, the data sources it will utilize, the algorithms it will employ for decision-making, and how it will continuously improve through user feedback and experiences.

Instructions: Focus on creating a structured and detailed plan that covers all aspects of the virtual assistant's development, from its initial design and training phase to its deployment and ongoing optimization. Consider the user experience, privacy and security measures, and how the virtual assistant will handle complex queries and tasks efficiently. Your response should demonstrate a thorough understanding of AI programming principles and techniques, showcasing creativity and innovation in your approach.