2. Shift+click, as you said, the line drawn is "wrong looking"; the only reliable angle for shift+click are 45° and.. if you click carefully you can also get the correct line for the tile angle (26.6° should be?). But I almost always draw lines with that angle by hand, because it's easy to get a "wrong" line so I just draw it. I wouldn't miss this functionality; I think that it could be left out if it requires effort to implement, unless there's an explicit demand for it.
3. If by area selection you mean the "Select colors" tool in contiguous mode, then it could be useful. I think it shouldn't jump diagonals because that is the behavior I'm used to (provided I understand the thing correctly).
But don't listen to me alone, a lot of my feedback is "I use photshop in this manner so it should be the same", which isn't exactly the best thing.
We should really page XOps because he uses more software and knows photoshop better than me, and Ryskeliini who is a better pixel artist than me (I cheat).