maddog, I would argue that there was in fact a SPARTAN-I program. ilovebees was a clever advertising bit done by Bungie, and one of the main characters' father is a Spartan 1. ilovebees takes place just before Halo 2, because it ends with the sirens on Earth telling of the Covenant attack. The original Spartans were just really hardcore soldiers with a lot of training, whereas the Spartan-IIs were augmented, and conscripted as 6 year old children.
Concerning the suit: I haven't seen this pointed out yet, but the original Mark V suit did not have shields. If they had shields, Sam would have been able to get off the Covenant ship in Fall of Reach, in fact, Sam wouldn't have ruptured his suit in the first place. It has been mentioned in other threads that the way the suit is structured indicates that it is older than the suit seen in Halo: Combat Evolved, and that it does not have shields. I believe the main point for this argument is the shoulder guard.
Concerning Harvest: Harvest fell, and the only forces that fought on it were forces in the immediate area, and they were all killed save for a lone ship. The ship didn't have Master Chief on it, or he wouldn't have been briefed on the Covenant.
Concerning Sigma Octanus IV: Sigma Octanus IV was a human planet, with a population center called Côte d'Azur. The Spartans landed on the planet, saved some survivors, then intercepted the Hunters with the rock from the Museum ([cough]Forerunner artifact[/cough]). It mentions in the book that Sigma Octanus IV, or at least the area around Côte d'Azur, was very lush. The Spartans sneak up on a group of Grunts in the forest. The Warthog trying to escape to the UNSC command post gets stuck in mud, then runs along a river trying to escape the Banshees. These are not things you find in a barren icey wasteland. However, like Earth, some planets have icey regions and tropic regions. I'd bet even Reach had cold harsh regions somewhere. However, on Sigma Octanus IV the UNSC knew the Covenant was coming, and thus they would not be surprised by the Covenant on the planet. Also, Sigma Octanus took place after the invent of shields (as best as I can remember) or we would have lost James to those Hunters. I only wish I still had the book (lent it to a friend who I don't see at all anymore) to confirm my memory...it has been about a year since I reread the books...
Concerning the other Spartans: There were 60 Spartans during training. If my memory is still functioning correctly, around 30 survived the augmentation and were fit for combat (about 5 or 10 were badly maimed and the rest died). In most of the engagements, the Spartans broke up into 5 man fireteams, so this supports the trailer.
Concerning Fred, Kelly, and Linda: Well, I believe Kelly is with Dr Halsey when the book ends. The rest of the...I beleive there were around 7 survivors including John that made it back to Earth, I'd guess they were stationed at different defense platforms. What would it matter if all the Spartans were on Cairo platform and it was held if every other platform was taken out with ease and Earth was still invaded? I would reason that Li and Will were stationed on the two stations that were destroyed in the beginning of Halo 2, if there were indeed Spartans on those (as I am sure there were more than 7 defense platforms). John was the only Spartan on the Cairo, so it stands to reason he was the only one on Miranda Keyes' ship when it jumped with the Covenant ship to Delta Halo. Thus, there would not be other Spartans on Delta Halo because only UNSC ship made it there just like with Alpha Halo.
I like pi.