Color: The color is Aegean Blue. It looks nothing like the sample on Thru-Hikers web site. I like the color a lot. It is pretty close to what the camera captured.
Size: I am 5'10" and 160 lb, 19" torso, 34" pant size. The fit is excellent. I might suggest leaving an extra inch or two at the bottom hem of the front panel so you have more options for length. I felt it came up a little short but it wasn't too short. The back was plenty long though and you can trim either once the project is complete.
Breathablility: I found the breathability to be very good. I do however live in a high and dry climate and can't speak to how it will feel on a humid summer day. I think if you are wearing it to keep the wind or rain or cold off then you will probably have no issue with breathability. If you are in the sunny south climbing a mountain it will get clammy.
If you decide you want a hood this is a good one to integrate http://thru-hiker.com/projects/hood_pattern.php. You would add it instead of the collar. I used it for a Cuben rain jacket and was very pleased with the design and fit. It will be more difficult to sew then the rest of the jacket though. It's Curvy.
Good luck Nate.