To A. adore God as our creator, B. thank God for His blessings, C. beg God's forgiveness of our sins, and D. ask God for any worthy goal, but firstly heaven. Prayer may be extemporaneous or memorized, public or private, communal or individual. Attention, humility, confidence and perseverance are needed in all of these situations. Daily and at certain times such as rising, meals, projects, goals, temptations and retiring. Families should pray together at least once a day.
Children know their prayers if they say their prayers.
Yes, if we have a loving relationship to God. Persons in the state of mortal sin must first obtain forgiveness of their sins. We want God to answer promptly with what we asked. God hears us, but He may answer later and differently than we asked. God answers in His own time and way, which is better for us, even though we may not realize it here and now.