I didn't read all the posts so this could have been said already but she can't just take your baby, she could go through court and claim you as an unfit parent and then ask and be granted custody, but she'd have to prove that. I reccomend if you do or act in any way that could be frowned apon in court to stop and clean up your life style, even if it means a boring life for you.
If your friend is legally an adult and you both consent to the adoption then yes you should be able to proceed without complications.
Also if she wants the baby because you plan on adopting it outside the family that is another matter. You will have to show the courts why you don't want her to be involved in your childs life because judges usually like to keep children within their own families if at all possible.
Good luck.