1. First, do ho harm. Your highest priority here is not to damage your bike's frame. You need enough seatpost length to extend past the top tube lug.

2. If you can't use the seatpost the way that it is you have nothing to lose by trying to shorten it. I doubt you'll be successful unbending it because it's important to maintain near perfect roundness.

3. 27.2 mm is a common seatpost size. If you can't find a used one a brand new Kalloy shouldn't cost much money. If it was my bike that's what I would do.