The double click in pidgin has always been a bit glitchy for me, I usually triple click (or is it triple tap, stylus and all?) just for good measure. As far as getting the screen to 'wake' on IM I'm not so sure you can do that, since it seems that the only thing that ever wakes the screen is either input or a powerup/down, but I might be mistaken. Personally I just keep my volume at max and have all the pidgin sounds set to loud to be alerted to a message, still have to tap the screen once before typing but it's not so bad.