I have to admit that when I saw it was Elosha I "squeed." I always liked her character, and, personally, I found her death more "shocking" than Billy's. Also, Billy died a skeptic. Elosha (or Not Elosha) said Laura helped her regain her faith, and she was Laura's spiritual advisor too, so I think it made more sense for her to be the spokesperson in Laura's vision. If the Virtual(s) are also manifestations of "God" then it would make sense for a priest/priestess to be it's manifestation.
Also, in addition to the Virtuals all being people that the percipients "loved" in some way, if you notice, they all seem to have something else in common.
Going with "love" let's first review:
Baltar loved Six. His virtual has been (with one exception) Six.
Six loved Baltar. Her virtual has been Baltar.
So Baltar seeing himself shows that at that point, he loves himself.
In the deleted scene from Maelstrom Starbuck confessed to Dream Leoben that she loves him. Her virtual later is Not Leoben.
Laura saw Elosha, and Elosha was her beloved friend.
Notice anything else:
Six is the first to tell Baltar she believes in God in the mini. She talks about her faith to him. She is God's prophet.
Baltar, is now God's prophet himself. He began as a skeptic, but Virtual Six has been leading him along the path, beginning in Season 1, culminating in him being a religious icon himself. So, when he sees himself, he's seeing God's prophet.
Leoben is the Cylon who is spiritually "in tune." Starbuck saw "God's prophet."
Elosha was a priestess. Laura saw "God's prophet."
Now, if these are all the same entity...that could mean that it is God itself or, as it says, an "angel sent from God." I'm inclined to believe the former, not the latter.
Also, did you notice that in Crossroads, as the trial is beginning, that's when the 4 start hearing the music in snippets. I wonder why. I don't think it was just the proximity to the Ionian Nebula. Rather I think it had something to do with the trial. The trial really set off Tigh so much that he started hearing the music. Tory blew up at the press eventually. Anders was already under stress over Starbuck's loss. Tyrol and Cally were having problems and the trial was being broadcast all over the fleet. Also, it's as the trial looms that Roslin and Athena (and presumably Six) start seeing the vision/projection of themselves and Hera. There's something about that trial that seems to me to trigger the Four to start recalling their identity. I think it was some sort of defining moment in their collective past, maybe the event after which they chose to bury their actual identities.
Since Earth is a disaster, maybe what happened afterward is something like this:
The Final Five sat in judgment on "God" because "God" caused a war, a religious war on Earth that resulted in this situation.
Their verdict, however, was to acquit God. I wonder if the 4 ior some of them voted to acquit while the 5th didn't. That might explain a lot. If Dualla is the Fifth Cylon, it may also explain her anger at Lee for defending Baltar - she knew the verdict, because she had seen it happen before, or maybe the Fifth, like Adama was persuaded to acquit "God" and, over time, has come to regret it.
And thus it makes me wonder if "God" isn't also leading the Colonials along the primrose path for some reason. If it caused the war and is trying to gain a following, maybe it's goal is to do what it did before.