بسم الله الرحمن الرحيم
(1) We could not find any hadith related to using four cups.
(2) In the lifetime of the holy Prophet Muhammad (صلى الله عليه وسلم) blade was not available. Hence how it could be sunnah to do hajamah with blade. The blood was taken up by any needle-like thing.
(3) A doctor may understand it better. We cannot give any opinion about it. No sunnah method has been told in it.
Allah knows Best!
Darul Uloom Deoband