I like kubernetes.io docs. You can learn from tasks, concepts, tutorials and docs itself.

I Like IBM Plex Mono

I like Oceanic Next https://marketplace.visualstudio.com/items?itemName=naumovs.theme-oceanicnext

Like you said, a Senior developer will give the shortcuts your team needs. I think is a good alternative from a startup that need to grow fast.

If you like the environment, start make over delivery of your duties and results will come.

I handle env variables at build time with webpack. If you wanna a staging and production env you can create one bucket for each.

Create a S3 bucket > upload your static files > Go to properties and allow static web hosting. You can find a tutorial at AWS S3 docs.

You can push your static files to AWS S3 bucket and serve with CloudFront. I'm using this away in my projects. On ClouldFront you need to config to always returns de index.html.