Claude's Pro plan enough for developing a startup? Questions about API and integration

Hi everyone, I am planning to start using Claude as my primary tool for a new startup project and wanted to ask the community a few questions before investing in the Pro plan. My main use cases would be: Basic legal advice and document review Brainstorming ideas and product improvements Implementing AI features within the app I plan to build What concerns me the most is this: Can I connect the Claude assistant (via API or similar) directly to the app I will create so that my users can interact with it? My s