If this Revelation is legitimate and applicable to us today then the result should be that we are all blessed by reading and hearing its contents. Perhaps the reading or hearing, by the Spirit, blesses us in some manner or way that we cannot comprehend in our flesh but our spirits are fortified thereby. It cannot be doubted that the writer meant to immediately impress upon the readers or hears the importance of attending to these things of this book because either everything (or somethings) were going to happen soon. Additionally, it's worth noting that this is the only book in the Bible of which carries a "special blessing" for those who read, hear, and keep its contents. Because of this we have to confidently assume that its contents are understandable.
Perhaps all of our limited human attempts to capture the real meaning of the book are failures because we keep trying to box a God and His revelation into our extremely limited views.
In the New Testament, Asia is not used in the large sense that we use it today (meaning the whole continent) but in its largest application is only referred to what is called, Asia Minor. It could have been that the Seven were the primary churches of that day. The number seven is evidently a favorite number in the book of Revelation. The phrase "seven Spirits" is only used in Revelation. A lot has been written of the Seven Spirits, and it is still impossible to determine with certainty who or what they are or mean. It is thought that since these Spirits are called the Spirits of God, and God is deity, then these spirits are expressions of deity, seven in form, possibly seven characteristics of God, which He sends into the world by and through His Holy Spirit or breath.
The phraseology "from him which is, and which was, and which is to come," is purely Jewish, and probably taken from the Tetragrammation, (HWHY) pronounced by us as YEHOVAH, a name that apparently includes in itself "all time" - past, present, and future, or as John reports, this is a Revelation from him "which is, and which was, and which is to come." So here John is pointing out that this revelation is coming from a being who is from all eternity.