wow, don't panic yet... I don't think this is normal and no , they are not all like this.
My advice would be to do the playpen thing and have her nap right away in the morning as well. A tired kid is a problem. Draw a line in the sand and let the parents know they need to help with the bottle thing and by having a regular bed time.
She is like this for a reason. If things don't improve you may have to term in the end.
As you said, the other parents are likely to be even less patien with her hitting and biting.
Good luck and keep up posted!