1. From my point of view, I don't think that learning the IPA
(International Phonetic Alphabets) is good as you just benefit from
how to memorize the pronunciation of a word, not the whole
spelling. Furthermore, sometimes, you cannot recognize the words
clearly and quickly because of the totally-different spelling.For
example: gourmet
So, it is suitable for you to put slashes after the vowel's part of a word
eg: a/phlo/gis/tic
For the symbols, I think you should memorise what it looks like or
the characteristics.
2. Basically, it is no difference. Definitely, you may be more familar with the methods through listening from the teacher.