As for Obama and Lynch and Holder - none of those will ever be brought to justice, so not sure why you expect that. That is way too much - it shouldn't be but that is the reality.
I think the most we can expect is for Comey, McCabe, etc to be charged with leaking, lying to the FBI and if we are lucky illegally obtaining warrants and bringing false charges, but I suspect it will only be leaking and lying. Lower your expectations and you won't be disappointed.
Of course a president can initiate an investigation. The president is the boss of the ag. He is elected to be so. The ag is not elected. If the ag or doj lets criminals go the president has to get busy. In this case we are talking about theworst criminals in american political history. If he misuses the doj, the congress can impeach him.
He should have handed Sessions the comey report and file and asked, can ou move this to indictment. If he said no, he should have picked someone else. The comey report lists her crimes and national security violations. Then he should have ordered the foundation and uranium investigations expedited including the pay for access funds into the foundation and the Haiti scam.
Raise your expectations or you let these people ride off into the sunset and rip the heart out of the rule of law.