I agree with your interpretation on the Sessions post. He could be like the Tortoise vs the Hare, just keeping his head down and quietly pushing forward with the investigations. Would explain why he has survived all of the calls for his scalp. If this is the case, it is a miracle that none of it has leaked.
Sessions legally walled himself off from any and all matters concerning the 2016 election via his public recusal.
Everything that Mueller and Congress are currently investigating, is directly or tangentially tied to that election, therefore Sessions is bound by the rules of recusal to refrain from participating in any investigations concerning such.
If Sessions truly is 'working behind the scenes, he'd better not leave a single finger print on his work product, or it will all be thrown out by the courts.