Choco I'm not sure there's any such thing as normal! All children waiting for adoption have suffered loss and rejection. Many have suffered abuse and trauma too. As an adoptive parent you need to be able to cope with how this might manifest itself in your child's behaviour.
Adopting my DD was the best thing I have ever done, she is gorgeous and wonderful and loving but always at the back of mind is the knowledge that she will always need more loving, more support, more care, more time, more patience than a 'normal' (knowing no such thing as 'normal' actually exists) child because of the crap she had to deal with before she came to me.
I'm sure you are going into the adoption process with your eyes open. There are some horror stories around, and in my limited experience the social workers certainly share lots of the worst case scenarios with you at the prep stage. But this is because they have to. As an adoptive parent you have to be prepared to acknowledge the potential 'worsts' that might arise. They might never happen but if they do you've got to be able to cope with them.
From other adoptive families I know I would say the best thing you can do for your child is acknowledge their adoption and the impact this might have on them now or in the future. The worst thing you can do is shut your eyes and cross your fingers and kind of hope it never comes up.
I would say I have been really lucky with my adoption experience. I think and hope my DD would say the same but this is not to gloss over the fact there have been lots (and lots) of times when it has been really bloody hard and I have cursed the inadequate adults who let my daughter down, made her anxious, scared and hypervigilant, made her unable to sleep on her own for fear of what might happen, made her scared of loud noises, made her wonder if she really deserved to be loved, and who still continue to have a negative impact on my gorgeous girl long after they have been removed from her life.
Adoption is wonderful and joyous and fulfilling (hopefully for both parents and child). Yes be prepared for the worst but make time to enjoy the best too. There will be lots of best times, even in the darkest moments. Best of luck with it all.