What should I do? what should I learn? any good book or path you would recommend me?
Look at the Mobile Makeover Guidelines, Web Apps section. I used that information to build this web app (view it on your iPhone): http://bit.ly/aewebapps
but after looking for some books to get in html5 and css3 it seems that all of them assume you have a deep knowledge of xhtml and css2.
HTML5 and CSS3 are but extensions and additions to (x)html(4) and css2(.1). If you want to be confident with the newer things, you'll have to invest time in the older ones. Especially HTML I think, since building web apps is a place where you really should use the right tag for the job, or know when it really matters (esp with regards to accessibility).
HTML4->HTML5 != Perl4->Perl5. It's not so much an upgrade, but additions and whatnot.
I also think that you start with some of the older stuff, you've got to learn the basics before you can fully use the new fancy things anyway since as Poes rightly said HTML5 is more new additions than a remake/upgrade of older HTML.
There are vast collections of books on HTML & CSS, depending on how far/good you are you might want to check out some of the Sitepoint starter books such as: http://www.sitepoint.com/books/html3/
Another place to start is http://www.w3schools.com/ - Some people say they are "mainstream crap" but I've found most of their tutorials relevant and intuitive.
I doubt enough people will? Considering that they are pretty much almost on the top of google search queries, they must have some good SEO and a decent amount of visitors every month. No luck talking to them directly, asking them to up their game?
DDG will remove stuff the community in general states are spammy... that is, you know how sometimes looking for a product on Google would bring up all these .cc domains with fake brand-name stuff? Google got lots of complaints... or eHOW showing up a lot for things... content mills and so? DDG removed them from search results as an easy way to have more relevant, non-content-mill non-fake results.
For google I assume it's harder to deal with, though they also do. Plus I guess if you start blocking a resource, next thing is blocking hate speech (who'd be against that?) and from there it goes downhill.