Does everyone have a guardian angel?
Yes. When the apostle Peter was arrested and ready to be killed, everyone expected him to die, but they prayed for his release, anyway. The Lord caused him to be rescued through a miracle. But, nobody expected this. So when he appeared at the door, a girl answered, and ran to tell everyone. They didn't believe her, and said "It is his angel," meaning his guardian angel. (Acts 12:5-15) There are other instances where angels have appeared to help people.
However, angels do not normally take the form of human beings. There may be rare times when they do. The Bible says that people have "entertained angels unawares." So, it does happen. There have also been rare instances where people have felt the presence of angels protecting them. But, usually God sends people to help. And, angels stay in the spirit realm, doing things like keeping a horse from throwing its rider, or keeping a person from getting hurt some other way. Angels take their orders from Jesus; we never pray to them, and we can't order them around. They are more powerful than us. (Jesus became "a little lower than the angels" when He lived on earth.) But, when we pray to Jesus, if the spiritual battle is in doubt, that prayer can tip the balance in God's favor.
