Hello....Hi, i am from India and right now i am living in china i have Z-type VISA

Sir, Anybody can suggest me on my query;
I have Z-type (work purpose) of PRC. And my wife has S1 dependent type. Now i wish to invite my parents to come for the purpose of foster care. (Right now my parents are living in india).
So, which catagory should be issued for my parents i.e. S1, S2, Q1 and Q2. from these, which one is suitable?
Also provide me information regarding the documents process or procedure for application and required documents.
Right now i am living in PRC, so which types of documents are required from my side??
After getting the entry permit from INDIA, do they need to medical examination in PRC??
Once they arrive here then what kind of formalities should be done??

How long they can live with me???

Thanking you,
with warm regards,
Dr. Rohit