best on my understanding, i will try to answer to your questions , other experts as welcome to advice as well
Question 1:
→ with Current Scenario in Quicksight
You can add up to 10 data sources to a scenario.
Up to 20 visuals can be selected from a dashboard at a time.
Uploaded files must be in .xlsx or .csv format and can’t exceed 1 GB.
Data sources can have up to 200 columns
Question 2: QuickSight Updates in Quick → No Quick does not bring in new visuals type. Quick is the top of the umbrella where QuickSight is the BI component which has the visual types. other new capabilities includes below
Amazon Quick Flows: Automation feature that enables you to create intelligent workflows combining AI reasoning with business actions across multiple systems without programming knowledge
Amazon Quick Automate: Process optimization capabilities that streamline routine tasks and workflows
Amazon Quick Research: AI-powered autonomous agent that combines organizational data with web search to deliver expert-level research reports with verified sources and citations
Amazon Quick Index: Data discovery service that helps you find and understand your organization’s data assets
Custom chat agents: Specialized AI assistants that use your organizational data that you can build and customize
Spaces: Allow you to create custom knowledge bases that organize documents and dashboards with controlled access permissions for specific business contexts, including file uploads, dashboards, knowledge bases, topics, and actions
Actions: Enable you to connect third-party applications and your own APIs to Amazon Quick for workflow automation and reduced context switching
Knowledge bases: Enterprise-scale document management that connects to data sources like Amazon Simple Storage Service (Amazon S3) to automatically index and search large document collections
Extensions: Platform integrations like Slack that bring Quick insights and actions directly into conversational workflows where teams already collaborate
For Question 1 with large data set may be you could use knowledge base but again it will be like LLM answering to your prompt not sure if scenario kinda of response you may get.