Recommended resources to learn SEO? Where to start? Projects? A few questions as I jump into SEO, coming from a background as a Social Media Manager (internship position)

Background: I bought a course on Udemy to get started but it's been very stale/slow (I know, all the info you need out there to get started is free but I felt like video course would help me lay the foundation/basics coming in as a novice, which it did). Powering through it and going to move onto different resources.

I know there is only so much one can learn in SEO with just theory and reading, and much of the learning comes from actual practice and implementing SEO into a project (similar to learning coding).

I'm coming in with some front-end developer/web developer experience (self taught, was trying to go the dev route but I just couldn't see myself in it as it got more advanced), so I've started to realize I do have a solid understanding of on-page/technical SEO already (meta data, title tags, accessibility, image optimization, html elements, UX design) which I feel give me an upper hand as well.

4 main questions:

1. Recommended resources to learn SEO? Blogs to follow, guides, MOZ, backlinko, ahrefs, recommended reading, books, articles, videos, tools, etc.)? I want to live and breath SEO for the next 2 months, before my internship ends at the end of Oct., so I want to digest as much info as I can on the daily
2. When to begin implementing learned theory into practice?
3. Best way to begin implementing SEO into practice? Project ideas? Create a website/blog/online presence and get it ranked on Google is the usual answer? Any advice for this? This just seems like a very general thing so I'm unsure of where to start and what topic to pick, something niche?
4. Career advice for landing an SEO-related position to begin my career in digital marketing once this internship ends? I currently work (part time) as an intern for a nonprofit as a Social Media Manager, so I essentially just manage their social media profiles; sourcing info to be posted, creating social campaigns, content, excerpt, graphics to be posted on social channels, schedule social posts based on implemented strategies (frequency of posts, best times to posts), use Hootsuite, analyze data in excel, keep track of KPIs - all very basic/surface level, but I got this position with absolutely no digital marketing experience (BA in Sociology). Luckily this position I feel like is an "umbrella" category over SEO so I feel as though SEO could be a logical next-step for someone in my position who wants to begin a career in digital marketing.

Sorry for the long post, I'd appreciate any helpful answers towards any of the question I listed, or any other info you may have! thank you! :)