The canvas hood may seem tight a first, but it will fit the frame once allowed to adjust to being out of the bag. the creases shoudl disappear to once it has been allowed to stand for a while.
The canvas will stand a light shower but it is 100% cotton and therefore not weatherproof and will fade if left for long in bright sunlight. If it does get wet, dry it thoroughly before packing away. If the site is not sheltered you can secure the canopy with guys ropes, however it is not designed for windy weather so should only be used with light winds.