Connection between Earth, Moon, Theia, and asteroid belt? Are there other fragments aside from the Moon that resulted from the collision of Earth and "Theia" (as it's called in recent main-stream press stories)?  And if not, why not?  And what happened to "Theia" (like were did it go?)

Has there been any consideration or hypothesizing that Earth may have had a larger orbit (say between Mars/Jupiter) until a large body (Theia) bashed into it, sending Earth closer to the sun along with its new satellite, while also creating the asteroid-belt?  Could something like Ceres be the missing "Theia"?

I know it sounds a bit far-fetched, but then so does the whole concept of the Moon being born from a planet collision with Earth (with very little evidence to back it up, at least till recently).
Let's start answering your question in reverse. Ceres could not be "the missing Theia", because of its shape. If an object hit the Earth at an angle (as is currently thought), it would be pretty deformed, if it managed to stay together. If it hit the Earth head on . . . Well, it would almost certainly not survive. So if it did survive the impact, it would be in pretty bad shape. Where would such an object go?

Let's investigate the idea that it went into the asteroid belt. That begs a question: Where is it today? Ceres is the largest object in the belt (and we've already ruled it out). Theia had a mass about that of Mars (see Canup (2012)). It's safe to say that if Theia survived with much of its mass intact and then disappeared into the asteroid belt, we should have observed it by now.

Now for your belt-formation theory. It is, admittedly a very cool idea. The mass of the asteroid belt is about 4% that of the Moon - so it could be the result of the planetary crash. And some theories say that the belt is, in fact, the remains of a planet. There is, of course, one problem - the different composition of the asteroids. There are three types, differentiated by their composition - C, S, and M. So it is very unlikely that they came from the same planet. Meier et al. (2014) show evidence that indicates Theia's composition would have been more like Earth, containing enstatite chondrites instead of carbonaceous chondrites.

Finally, let's look at your idea about the Earth having an orbit farther out. This one seems to have a good chance of being right. The early protoplanets in the Solar System were very - very - unstable in their orbits because of the frequency of collisions. So the Earth could have been in a different orbit early on, and then migrated inwards or outwards, though planet-planet scattering or perhaps gas disk migration.