As far as the receeding galaxies going faster, I think I may have a few questions that might shed some light on it.
1> Is there such a phenomenon as gravitational lensing?
2> If so, do scientists take it into account when judging distances of other galaxies?[Quasars are thought to contain massive black holes. Such objects would likely create some pretty nasty problems in the wavelengths of light]
3> With respect to your idea of an expanding sphere, Not A Poet, could it be that the distance is affecting the impulse on the galaxies' momentum? We know that gravitational force is proportional to distance.
Finally, about that question of why it's expanding in the first place, I posed that to challenge the idea of infinite mass. If the universe was infinitely massive then it would not be able to expand much, because there would likely be a uniform distribution of galaxies throughout infinity. Either that, or else there would be a few places[namely black holes] in which the mass was infinite, and so they would be sucking the rest of the universe into themselves.
It can be argued, however, that the cosmic singularity[I think that's the name for the "seed" that started the big bang] was finitely small, but infinitely massive. However, this would still result in infinite gravity, as you've said, Not a Poet. That's why I stick to the idea of a seed that has incredible mass, and that explodes with enough force to send this mass careening in every direction.
There is also another problem:
The galaxies in the known universe all seem to be uniformly distributed. In my opinion[although it's not really backed by much] it is due to a uniform distribution of mass throughout the universe. But if what I've said is true, then why does the universe's mass happen to be so well distributed?
THis leads many to think that there is dark matter. This is because we often see rings of galaxies surrounding regions of complete darkness. But these rings all seem to be well distributed.
So, Not a Poet, I'm with you as far as a finite universe is concerned. This is probably due to the fact that I always see the universe as having a beginning, or else at least continuing to cycle in Big Crunches and Bangs, at regular intervals. The idea that "the universe was just always here" doesn't sit well with me.