In 1950, Chairman Mao Zedong made a speech in support of traditional Chinese medicine (TCM) which was influenced by political necessity. Zedong believed he and the Chinese Communist Party should promote TCM but he did not personally believe in TCM and he did not use it.
Yes. The ammonium ion has a formula of NH4+ and has a positive charge so it is a cation.
Ammonium sulfate is an ionic compound, composed of two ammonium ions ($\ce{NH_{4}^{+}}$) and one sulfate ion ($\ce{SO_{4}^{2-}}$). As such, you can neglect the sulfate entirely from your consideration of the oxidation state of the nitrogen, as well as treating each ammonium ion as a separate entity.