Why did Ed draw a circle?....Why does Envy look like the 'present' Hohenheim?? FullMetal Alchemist.....?

I'm not sure about number 2, but Episode 5 was before he knew he had the abillity to not use the circle, it was before the exam even started. In the exam he didn't have time to draw a circle and save the guy from the falling thing (not reall sure what it is right now) so he clapped his hands together, I thought it was pretty dumb how he just knew what to do.