We have bible veses showing that spirits have a body, they have feelings and they can pass out before Jehovah. They have different powers, according to their position and possibly having a dwelling place. The heavens are very likely another dimension we are not able to see, due to the limitations of our senses. Our mind though is made in God's image and can reach places our body can't. Our mind needs knowledge and through that knowledge we are able to see a lot of things. Jesus gave us that knowledge. He informed us about Satan's existence and about the kingdom of heaven. Before that, humans didn't know much about the heavenly realm.
The war in heaven very likely not literal. Mostly like a court room, where Satan and his angels try unsuccessfully to defend their precarious position. The real fight is on earth where every member Jesus's body successfully stands against Satan and his visible representatives. Once the members of Jesus's body are being resurrected there is no place for Satan in heaven, because the old organisation of Jehovah becomes Zion, and the old heavens cannot be part of it.