All possibilities exist.
lost the child to whom?
yes
Yes, this is possible if the child hasn't been adopted. or the mother could destroy everything the child has known and regain custody after they are adopted. This would be a very wrong act and it is not recommended.
This question cannot be answered. There are simply too many facts about the situation that are not known.
No, he shouldn't be able to if she is legally married. If she was underage at the time of marriage and the custodial parent signed off on the marriage and that should have been the end of parental custody.
see your other question
Unless you can show that your consent was given under duress or fraudulently, then you're probably going to have to talk to the current adoptive parents and convince them to work with you to regain custody. You can consult a lawyer with experience in these matters and give them all relevant details for a better answer that is more specific to your situation.
yes he should do
It is not very likely. The child is now legally the child of the adopting parents. Giving up the rights makes it difficult to get them back.
you dont
see links below
If the children are adopted it's not a question about custody since you no longer is the parent. It's very rare the courts break an adoption but it does happen but you have to have good reasons to. Speak to a lawyer where you live about your case.