First paragraph correct.
Yes, in English we do just use ny, and on;y in words borrowed from Spanish, but they are so much a part of my life, I just thought I'd add them. (You'd be surprised at the Hispanic population in my part of Oregon.) But think of X and Q. I suppose I could say Q is related to C or K, but, well, I've only started this in the past six months, and it isn't well researched. If you or any other surfer know of a free source for THE International Phonetic Alphabet, I'd appreciate it.
Y is actually the sound in-between ee and another vowel. So in oh-ee, you shorten the ee sound a bit.
There are two distinct sounds, oo and ew. oo has a long U sound, and ew is in mew like a cat but not sew. But then, when my mom says them, I can hear a very distinct difference, but when I do, I can't hear any. AND all these sounds vary from state to state in the U.S., and in England it's worse, and then there's Canada, Australia, etc.! So it's hard to give a letter combination a particular sound that never varies.
Say TSH as t'-sh' fast, with the apostrophe as a tiny neutral letter. Same with DZH. Y :)