Why yes, the bible clearly states the existence of Angels. They were created solely to do the work of God. The number of Angels has always been the same( except some of them are now fallen ). One does not become an angel after death.
Yes because I watch Supernatural, and according to the lore on there, there are allot of things that are real most people to not believe in or know about. Joking, but yes I do believe they are real simply because it make me feel good to think that some unseen force has my back. I believe that they guard us.
Yes, I believe in angels. However, it's all due to faith. Nothing can prove their existence. It's easier proving the existence of God than angels. One could argue that God is the cause of all things that exist, but what argument can be made in defense of angels? The Bible? Perhaps.
Well, If you have traveled to a third world country, miracles happen every day, demons are cast out also; America as well as modernized countries for some reason don't have as much or as noticeable signs of this. I have been fortunate enough to witness people being healed from broken bones/ other painful injuries. If you want some stories message me...