Yes.
Yes
Yes If the kid invites them in.
The police are supposed to try to contact the parents of a minor before they question them, however, as long as the 17 year old was read their Miranda Rights the police may question them.
Certainly a police officer can question a 7 year old.
If the child was alone and in 'strange' circumstances and the police found it necessary to talk to him, to find out information, yes they can. If he was taken into custody and questioned in a situation where it was clear that he wasn't going to be released then the parents should have been present.
Yes, police offers can question anyone at any age regarding a crime
No unless the minor wants to press charges
the daughter has to be a responsible and kind person who would take care and help her parents in anything
No No. Because your daughter was in a building does not automatically give you the right to trespass. If you feel that you can convince a jury of your peers that your daughter was in mortal danger AND that the police couldn't or wouldn't protect her.....go for it.
They can a rest your parents
Nothing can happen to the parents as long as the 19 year old and 15 year old are not having sex.
No. That is her fiance, because of their relationship he can not be her legal guardian.