I loved the expression on Walt's face when Mike told him off. He knew every word Mike said was 100% right. Walt fancies himself a badass, but his move to kill Mike was desperate and pathetic and succeeded only in spite of his incompetence. Well-played.
I, too, wonder how the DEA got the lawyer to roll. Having a bunch of money isn't illegal, especially if you're a lawyer, and it doesn't seem like anything blatantly illegal could've been determined just from the safety deposit boxes. That lawyer must be a real tool to flip so easily under so little threat.