You make some great points. I agree with you that the flashbacks to how each of the Oceanic Six arrived for the flight will just be cushioning -- Hurley said it himself that it doesn't matter how he got there... So why'd they keep it a secret? I honestly don't care if Charlie came to speak to him and they are holding out for Dom Monaghan to come back. I don't.
We are getting somewhere, that is obvious, but it is clear that there will be unnessary digressions.
Also -- something cool that I was thinking about. I didn't know what a proxy was until I looked it up this morning. If you don't know, it's essentially a substitute for something significant. Locke, for instance, is standing in for Jack's dead father (which I thought was by far the most cool thing the episode set up), but who are the new characters standing in for? Well, turns out there are proxies other than Locke. I think the air marshal is the proxy of Ana Lucia... A female law enforcer, duh. The other guy who was on the plane I think will be Libby's proxy. I think she was an agent for Widmore and I think the same for him, too. It's no coincidence that they are throwing these new characters into the show. And lastly, Lapidus is the proxy for Seth Norris. That's another reason why I think he'll end up at the smoke monster's mercy.