In short(ish), there's no rush on bringing Lehner up, and Anderson is playing fantastic hockey right now. We have 2 more years for Andy to fall apart, or keep playing great. Andy is one of the few goalies that spent a large amount of his career in the back-up role. Colorado named him starter, then made him play for his job- their loss, our gain. He wanted out of Colorado because of the way they treated him, and we should let him run with the ball as long as he's playing so well. If/when he falters, bring Lehner in to put the heat on him.
Montreal could have got more for Halak if everyone in hockey didn't know that he had to be moved.
You didn't say put Bishop on waivers, but you want an Anderson/Lehner tandem. I read between the lines. Not sure why you think he could have landed a 2nd or 3rd rounder besides reading posts on HF. His acquisition probably secured us a playoff spot last year, though, so I can't see how you'd bash it.