A React-only application is harder for search engines to read. For pages that must be found on Google, we use Next.js, which produces readable pages on first load.
Not automatically. Next.js offers an excellent technical base (speed, structure); a well-built WordPress site also ranks very well. The choice mainly depends on the features you need.
Yes, it is one of its strengths: it can be used for a single form or screen, without rebuilding the site.
They are two different frameworks despite the name. AngularJS (version 1) is no longer maintained; Angular (version 2 onwards) is the current version, rewritten in TypeScript.
For an application with many features, Laravel brings proven building blocks (security, accounts, email) and a standard structure: development is faster and the code easier to take over.
Both are excellent PHP frameworks. Symfony for very structured applications maintained over the long term, Laravel for fast development. If you already use one, we stay with it.