This is GREAT. I have always had an issue with tone 2 and 3 but it turns out I have this tiny dip before the rise in my tone 2. It took a while looking at the tone patterns before I worked it out. Now give me something for that stupid ü or u-umlaut and then I might actually sound ok.
That's actually fine. (I'm a native bilingual speaker, although not from PRC.)
Also, the 3rd tone is characterised more by being low than the fall-then-rise. In fast speech the rising part is often not heard; it's only really present in stressed syllables or possibly at the ends of sentences.
yu combines the tongue position of yi and the lip rounding of wu. Being able to take apart the individual components of a sound and consciously reassemble them into something different is very helpful for language learning.
If you're not sure what the components are, try reading the corresponding Wikipedia article (usually linked in the phonology section of the article about the given language): https://en.wikipedia.org/wiki/Close_front_rounded_vowel
