What did Jesus mean by calling himself the beginning of God's creation? The Koine word arche could refer to a preeminence in time (i.e. "beginning" as in many English translations) or preeminence in rank (i.e. "ruler" as in the NIV). Though "the Beginning" is an important titular designation for Christ in the Revelation, when it is used as such, it is always coupled with "the end", and within the immediate context of the letters the parallel designation, "first and last", is used (on a related note, see this). Given these considerations, and the fact that Christ's authority is the general theme of all his introductions in the letters, I think that "ruler" is the preferred sense in which the word is used here as is attested by the choice of NIV translators.
What I think is undoubtedly not meant by the use of arche is that Christ was the first creation of God as heretical movements past and present have asserted (e.g. Arianism, Jehovah's Witnesses). Even if it may be that the Son is "eternally generated", he is not created--he is, in fact, part of the nature of the Godhead. God is Father, Son and Holy Spirit, which is what he always was and will be always what he is. There is distinctiveness within the Godhead, but always unity as well, and even though there is no way to tell the divinity of one member apart from the other two, it is always possible to tell their personhood apart.
Despite my earlier statements, there was at least one use for lukewarm water commonly held in the day of John the Revelator. Even today, particularly in home remedies, tepid water can be used as an emetic in conjunction with salt or mustard or a finger to the back of the throat. So it was particularly fitting that Jesus threatened to spew the Laodiceans out of his mouth. When we consider that the word translated spew doesn't mean merely to spit, but instead to vomit, we see the clarity and fittingness with which Christ expressed his disapproval of these folks for their indifference.
"Be zealous and repent" was the response Jesus called for to his rebuke. The word translated zealous (zeleue) means to boil with fervent passion, as in jealousy or desire. That, of course, plays upon his earlier statement that the Laodiceans were neither hot (zestos) nor cold. The issue there was not their temperature but their usefulness: cold water was useful for refreshment, hot water for baths and washing, lukewarm water was good for nothing (except a purgative). In this rebuke Jesus tossed aside the idea of refreshing (cold water) because the Laodiceans did not need refreshment--they needed to be passionate in action (heat).
If there ever was an antithesis to Jesus' key authority, "Behold I stand at the door and knock," would be it! Despite the use of this text in evangelistic tracts and presentations, this text actually has nothing to do with evangelism (an appeal to the unsaved) because it was written to the church. Nonetheless, it does fly in the face of both the concepts of irresistible grace and the perseverance of the saints. After all, Jesus isn't just unlocking the door because he's made an election by predetermination, but he's making an honest invitation for which the implication is that it could be accepted or it could be turned down.
Those who open that door get to dine with Christ, and those repentant souls who overcome get sit down with Christ on his throne. Truly, his rebukes, even if seemingly harsh, come from love.