The particle は[ha] is read "wa".
"Wa" performs as a contrastive marker in #3 , i.e, it's used in a context that "I don't like to write kanji (but I like to do another thing, for instance, to read kanji)".
#4 sounds a bit awkward. It should be "Kanji o kaku no ga kirai desu ga yomu no wa suki desu" or "Kanji o kaku no wa/ga kirai desu. Yomu no ga suki desu".