2. true to a certain extent, but some costumes allow for a larger height range (couple inches)
3. false, heads of all sizes are fine as they will adjust to your head size
i don't know what your chances are if you audition again. you might be hired and you might not. you may have been cut due to dancing/acting skills, or because they changed their mind about your look. just because you passed the look cut, doesn't mean that you won't be cut for your look later.
you might have also been let go because they weren't looking for your character at the time, but they probably would have told you that. otherwise, they tell you to come to another audition.