Going back to Walt's cancer, I'm pretty sure it's back. I went back to review a couple episodes when Jesse was talking about his aunt's cancer, and that fly showed up when he was talking about it. Same with the fly in the last episode. And the dispenser that he punched back in season two. All is symbolic with it being back, in my opinion.
As far as Hank vs Walt goes: I'm conflicted with how it'll go down. A part of me wants to think that he'll help Walt get out because he's his brother-in-law and he's stated repeatedly that he's tired of his job. He'll confront him, they'll discuss everything, Hank will warn him about what's about to happen, and he'll get out.
Another part of me says he's embarrassed that everything happened right under his nose, so he'll trail him for a bit before going in. He'll definitely be conflicted for a while. I'm curious as to how he'll approach him. There's really no evidence, especially if Walt really is out. Everyone is dead except Jesse, Todd and his uncle, Saul and Skyler.
No idea.