I don't own this but it is recommended more than any other in my watercolor groups.
It's a book, not online, but this is the best overview of materials and techniques I've found. It's easy to understand and has plenty of pictures to help you understand. I got it after I'd been painting for a while and considered myself half-decent, but I still learned a lot from it.
As for a website handprint is very comprehensive, though word-heavy and doesn't have as many pictures. I would recommend it once you get past your beginner hurdles want to start getting into more advanced techniques and concepts.
Watercolor pencils are a good way to get started in the medium and see if it's for you, but if you want to get into it I'd recommend graduating to pans or tubes of paint. Pencils are good for laying color on the page, but it can be hard to execute basic techniques with them as opposed to traditional watercolor mediums.
As for tubes: I personally use them like the 'cakes' you mention by squeezing the wet paint into pans like this and waiting for them to dry. For a beginner I wouldn't suggest using wet paints, as it can be easy to overdo it as opposed to dry pans where you can build up layers of color.