S2 visa 180days

I am planning to go to China visiting my sister. her husband is there on a work Z and they have 3x daughters. youngest one born in China (5months) is the S2 the correct one I can apply for? I would like to stay for a year. my question is I am planning on flying with them on the 3rd of August 2018. I have got all the documents (invitation letter (detailing the time frame), passport photos of family in Beijing, my own, unabridged certificate of myself and my sister that we related) need to know if I must submit visa to Chinese embassy in Cpt (have submitted previous one in Jan 2018 for 15day stay, when baby was born) by myself or can I send someone else? and how long will it take once submitted? is there anything else I might need? I wont be working but family there will be supporting me and it states that in invitation letter.

Thank you
Nadia Myburgh - SOUTH AFRICAN