The DOJ/FBI are not a Fourth Branch of government. The Congress has oversight responsibility over them. Part of the checks and balances. The Congress; both houses, not only have the right, but they have a duty to provide oversight. House Intel Committee has subpoenaed these documents many, many months ago. They have threatened Rosenstein with Contempt and Impeachment, which they have the power to do.
To your first point. Could it be that they didn't find any unseamly information during the campaign? If you believe Gowdy, then not only did they have any unseamly info, they have never even been investigating Trump! You and I both know that's not true. (Comey's presser, Dossier, etc). Also, there is the questions raised by the Strzok/Page texts. They thought Hillary would win! In fact, they had a plan to help her win; code name, "Mid-Term Exam". In that event, none of this would even be a thing! When it started looking like Trump might have a chance, then they were texting about an insurance policy. Look, some of this could be clarified by the next IG report, which will be dealing with the Clinton Email investigation. We'll all know more soon. Next week, I think.
Don't think I'm wrong, but if I am, I have NO DOUBT, it will be pointed out by someone. The CIA was created for foreign intelligence and it is illegal for the CIA to target or spy on our citizens. Evidence of this, is the fact that the 5 Eyes agreement states that the 5 Eyes members agree not to spy on each other's citizens.
I'd like to see some proof that Nunes is responsible for leaking. A Senate staffer was arrested today for leaking.
One last mention of something to watch: McCabe is asking for an immunity deal. I'm extremely interested in how this is handled. McCabe, Comey, Brennan and Clapper seem to be forming a "circular firing squad", and Comey and Clapper are all over TV saying things that could be used against them.