Funrus

Practice a lot. And for example, you should try Skillshare. There are many nice video tutorials tha could maybe help you in many ways ;)

SEO is way bigger than PPC but you need to be very patient as others said! I've heard that you also need huge budgets to see some good results with PPC. Is it right ?

Speed of websites, schemas, and a HUGE focus on delivering quality content for users (and not Google)

For me it does matter a lot ! You should really have a link building mostly based around websites using the same language as your website. But it is not a problem to have some from other languages.

It's a day to day work, you cannot just stop unfortunately :)