Best way to configure Nginx caching for a WordPress site on a DigitalOcean droplet?

I’m setting up a WordPress site on a DigitalOcean droplet (Ubuntu 24.04, Nginx, PHP 8.3) and want to get server-level caching right from the start rather than relying purely on a caching plugin.

Current setup:

• Nginx as the web server (not just a reverse proxy in front of Apache)
• MySQL on the same droplet
• No object caching configured yet (considering Redis)

Questions:

1. Is it better to handle page caching at the Nginx level (fastcgi_cache) or rely on a plugin like WP Rocket/W3 Total Cache on top of it — or is that redundant?
2. For object caching, is Redis worth the added complexity on a single-droplet setup, or is it overkill unless traffic is high?
3. Any gotchas with cache invalidation when content updates (e.g., stale pages showing after edits)?

Trying to get this right from the start rather than bolting on caching later. Any config examples or gotchas from experience would help.