Hi again Kenisyes,
This is a long read so take your time.
Again having little experience as a worship leader I'm not sure I can answer your questions.
I guess I misled you (& maybe others) into thinking I've lead a lot of worship, when I have not, but I have played keyboards on worship teams as well as sung. However I will do my best to answer your questions.
I actually haven't heard of the 5 levels of song. I think it depends on the congregation. Not all churches are ready for, or want, the deep worship. Out of the 4 worship teams I've been on in 4 different churches only one was really and truly ready and desiring the deep worship. I consider deep worship (and again I could be wrong) songs like Holy Of Holies (aka Take Me Past the Outer Courts), True Love (Jesus I want to know true love), etc. - songs that talk of coming into His presence, desiring to touch Him, feel Him and be touched by Him. It's been my experience that some churches move too quickly from one song to the next, not really giving much time to sense if God is moving or not. I was one team where there were almost no breaks in between songs...they were played like one big long medley. It didn't seem right to me, but since the Pastor was the worship leader, and not really called into worship ministry, I did try (albeit unsuccessfully) to get him to not rush thru the worship set. But since I wasn't one of his "pets" he didn't take me seriously. I told him to try to let the Lord move but was ignored.
My heart's desire is to enter His most holy place and stay as long as He will let me, to be filled with His love, to know Him so intimately I can feel Him! Just thinking of it gets me excited.
I would go by the Spirit's prompting to know when to transition, altho as I"ve said not all worship teams do this. (I wish they did.) Constantly seeking Him and sensing for His spirit and presence is an important part of worship. If the congregation needs something more to get them into praising God, we may decide to switch songs in a worship set, or shuffle them around according the "flow" of the service. I also pray during worship for the Lord to move upon the people, show us if there's something He desires or wants changed, etc. I'm in constant touch with the Lord thru worship.
The main goals of rehearsal is for the team members to become familiar and also work on songs. We do have some songs in the same key but also sometimes have songs in a different key. (again lack of experience as a worship leader myself) If I recall correctly I think they offset the key changes by speaking briefly or sharing a Scripture, something along those lines. What matters most is getting the congregation into God's presence, keeping them there as long as the Lord wants and letting His Spirit flow.
I've only been on one worship team where the singers did harmonize, in that case it was only 2 of us- me & the Pastor. One other team had singers that could barely sing a note but were there because they were the Pastor's pets. The other 2 pretty much sang lead. Me, if and whenever possible, I like to harmonize. It comes naturally for me, I consider it a gift from the Lord.
Now....about my other music minstry calling...I have vast experience in doing solos aka "special music". When it comes to doing solos I again seek the Lord for the song He wants, and in some cases when requested, seek Him for a particular subject in the song. I prefer to sing songs that talk about Him directly, mentioning His name (or titles) and are not just about "love". I always want the people to know
who I'm talking about. Some songs are more anointed than others. I look for such material, because the more anointed the song is, the more powerful the impact (i.e. movement of the Holy Spirit) on the audience. I sang at a revival service once, and the song I did was so powerful the Lord's presence was very strong...so much so that I sang it about 3 times and each time, the Lord was touching more and more people. It was so beautiful. Another time, I sang the song "Watch The Lamb" for a Good Friday service and the power of God touched me to the point I cried thru it. I really love when God steps in!
I hope this helps.
Love in Christ Jesus & prayers, Lynda (Sing4theLordJesus)
PS - I would love to chat with other singers and musicians in worship and music ministry!