As I understood it though, FriarErasmus described something a bit different than either of these... sort of combining them somehow? (I'm not sure about this, so sorry if I misread his post.)

Not to get on my "soapbox" again, but just wanted to clarify my faith in this regard:
Yes, the concept is in some ways a combination of the two theories. It proposes that there was an original creation that either was created billions of years ago, or was created in an already "old" state. There is left open a whole wide set of options of how the world was prior to the first catastrophic Adamic flood. The scriptures do not speak too heavily of the Earth prior to Adam, just as it does not speak too heavily of the future new Earth (though there is more on that than on Earth prior to Adam). This makes sense because we live in the current Earth, and what happened before is only important insomuch as it helps explain the current state of things: Lucifer used to be king of this earth and was charged with the care of all people on this earth in the preadamite era (possibly guiding natural selection to bring about cromagnum man from a lesser creature over billions of years, so that allows for some of what you
might call evolution, though this is more natural selection, but we will never know exactly what happened during this time), but he was dethroned for attacking the gates of heaven. This gives him jealousy of Adam as a reason to undermine Eve, as Adam had supplanted him as God's favorite, God's friend, and King over Earth.

One key difference from the Old Earth concept - I still feel the account in Genesis is a literal one, as the gap between Genesis 1:1 and 1:2 allows for infinite time prior to the restoration of earth and the creation of Adam in the image of God. So basically, God literally created everything in the beginning. A time period we can never determine from scripture happens. Somehow during that time period, the earth is utterly destroyed and made formless, is covered entirely in dark clouds, and waters flood the earth. The Spirit of God hovers over the waters, and the Triune God decides that it finally has been long enough to completely wipe out all living things on the earth so He can start again. Verse 2 begins the literal restoration of every thing (explaining how there could be light, night, and day even though the sun, moon, and stars were not "made" or restored until the 4th day).
Anyone interested in more details or just wanting to talk, pm me, and we can start a new discussion on this in another forum.
Disclaimers: INTTCY and IANAF
(
I'm
not
trying
to
convert
you and
I am
not
a friar)