Hi there,
Thanks for writing in!
You don’t need to validate cornerstone separately, since you’re using X and the version of CS that comes with X theme is validated.
Slider revolutions comes bundled in X and you don’t need to activate it in order to use it. As long as x is activated you can use slider revolution without activation code.
In regards with image upload size, please check this link : http://wptheming.com/2009/07/upload_max_filesize/
In regards with missing content please provide us with more detail like some screen shots.
Hope that helps.