Definitely get the manual version. Ive owned three tis, 1.8L manual, 1.9L manual, and 1.9L auto and the auto is by far the slowest thing out of the three.
Id say, to be comfortable, the people sitting in the back shouldnt be more than about 160-180lbs and over 6'. Ive sat in the back of mine with friends to see what its like and i was comfortable, 5'10 140lbs. You will notice when there is extra weight in the car as well, whether with friends or with a lot of weight in the hatch.
As for the storage space, i put a corvette 5.7L V8 fully assembled engine, two crates, and a large toolbox in mine..
