After hair transplant, is it necessary to take a antibiotics? (like after lipo or implants surgery)

You do not need to take finasteride before or after surgery.  Finasteride is an elective medication than may be recommended by your doctor.

If you have issues after your hair transplant surgery it is best to follow up with your doctor.  There should be no issue with using any shampoo.

It is best to ask your surgeon about post operative care as each doctor has their unique regimen.   Everybody has a different perception of pain and only your doctor knows what was really done during your surgery. 

It can take 6 to 12 months after surgery to see results.  If you are concerned it is best to contact your doctor.  There is no way to tell if your surgery was a success only 12 days after surgery.

It can take 6 to 12 months after surgery to see results.  If you are concerned it is best to contact your doctor.  You will not likely see growth after 2 months.