MongoDB offers flexibility with its schema-less design, scalability through sharding, and high performance for read/write operations with its document-oriented storage.

React handles state with local state using useState, global state with Context API, and more complex state with libraries like Redux.

Middleware in Express.js processes requests and responses, performing tasks like authentication or logging before reaching the final request handler.

'async' and 'await' are syntactic sugar for working with promises in JavaScript. async functions return a promise, and await pauses the execution until the promise resolves, making asynchronous code easier to read and write.

SSR generates HTML on the server before sending it to the client, which can improve initial load times and SEO. CSR generates HTML in the browser using JavaScript after the page is loaded, which can lead to faster interactions but may affect initial load times.

CORS (Cross-Origin Resource Sharing) issues can be handled by using the cors middleware in Express.js, which allows you to specify which origins are permitted to access resources.

The useMemo hook optimizes performance by memoizing expensive calculations and preventing them from being recalculated on every render, unless the dependencies change.

Dependencies in a Node.js project are managed through the package.json file, which lists all required packages. You install these dependencies using the npm install command, and they are stored in the node_modules directory.

React’s PropTypes are a type-checking mechanism for validating the props passed to components. They help catch bugs by ensuring that components receive the correct types and shapes of data, which improves code reliability and maintainability.