Is it possible to set an overall seed for generating blocks on regtest mode? I am using bitcoin core on regtest mode to simulate sending transactions. 

Is it possible to set an seed for things like generating blocks or signing transactions, so that you can recreate an exact chain of events with the same block hashes and signatures?
Generation of blocks uses the proof of work algorithm that includes a nonce that ensures randomness, if we could somehow recreate all these things the whole system of cryptocurrency would break down. The short answer is no.