+ Location was irrelevant, traffic would come from Asia, Europe, America
It's totally relevent and a good proportion of your traffic will always come from the three locations mentioned. They are massive. In particular the Asians are making great use of the internet to search out potential customers. Just look at how google works now. Local this. Local that. In a way, unless you are a known International Brand, it is a bit like bricks and mortar, location, location and location.If you haven't signed up for Webmaster Tools do so.
+ SEO was irrelevant, I did not bother with keywords, I did not submit my site to any engine, I was too busy working on the content. Nevertheless, my site was soon indexed and it was quite highly rated.
Google hasn't used keywords in Meta tags for a long time. That kind of SEO died with the keyword stuffers. Remember the days you searched for chocalate and every site was a prn site. They killed keywords. True SEO will be gone in 5 years as Social Media sites will dictate search rankings which is why Google has invested heavily in +1.
+ Visitors coming from google search were usually random, one-time visitors, who mistook my site by something else, or who did not know how to precisely specify their search directive.
This can be converted to useful visitors by taking a look at your Meta Descriptions which is what appears below the link to your site in Googles results. Writing good landing pages with relevant content and good Description tags is critical.
+ Most, if not only, valuable traffic was coming via references from other, somewhat related, web pages
Thats exactly what I aim for but this takes time to evolve and relies on good content from your site. There are subtle ways of speeding this up but like anything to get a return you need to work hard and add a bit of lady luck.