Long story short – after years of being a developer switched to managing our own product team and finally turned to marketing (and sales) almost full time. Since then, I've been teaching myself and dealing with pretty much every area of online marketing – from strategy to content to email to paid to social to search – with mixed results. However, I feel like I still lack the big picture, the underlying structure of it all – so even when I'm doing great in one particular area (say, SEO) I'm never sure I should be in this specific area right now at all, especially when good results in one area don't move the business needle at all. The lack of work experience as a marketer really doesn't help here. Can you teach all of this yourself being your own marketing team? Do you find a mentor or hire a marketing person and learn while working with them? Do you just take a break from your business and go work in marketing as an intern? There are tons of great guides on every marketing aspect, but what's the best way to get the big picture right? I imagine that's something a new CMO goes through when joining a new company.
Unfortunately, it's impossible for a single person to focus properly on multiple big pictures, and many of the things you list here each belong in their own photo album. I've never met a stellar marketer who is also stellar at SEO.
Your best bet is to choose your real niche and then surround yourself with great players who also need people to bounce things off. I bring in other people all the time because - newsflash - you can't be great at everything. Focus on too much and the best you can hope for is mediocrity across the board.