I really like The Complete Watercolorist's Essential Notebook by Gordon Mackenzie. Amazon Link If you look into it make sure it's the "complete" version which includes his book on landscapes as another section in the book.
I really like it because it is very thorough on specific techniques, general artist fundamentals, and more abstract ideas like painting without fear while the book is easy to understand and enjoyable to read. Hope that helps!
I just received this for christmas - https://www.amazon.com/Complete-Watercolorists-Essential-Notebook-experimentation/dp/1440309051/ref=sr_1_5?ie=UTF8&qid=1514489489&sr=8-5&keywords=watercolor+book
I'm super excited to start digging through it! It's not written as a lesson plan or anything, but I plan to go through each topic/technique to practice from daily.
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.
From this one. I recommend it :)