你 vs. 妳 for second person
妳 is supposed to be the female second-person pronoun, but I don't find it being used as often as the more generic 你 anymore, however。

And no. There is no connotation re: breasts of milk with the use of the word.

Not sure why some posters have the assumption that 你 is only used for both male and female in Simplified Chinese. Is it how it is used in Taiwan? As someone who can only write in Traditional Chinese, it seems that 你 is used interchangeably for the most part (even among my friends from Taiwan on social media, and books from Taiwan, etc.). Some people do use 妳 for female, but it seems rather uncommon nowadays.