On sunday, not on the end of the reset
People simply had more time to get gear this time, especially with upgrades beeing around for much longer and the thunderforged loot.
That's the difference between the transition from T15 to T16, compared to T14 to T15 back then.
ToT was more about mechanics, even on normal, while SoO doesn't seem that way so far.
Lei Shen was way more taxing than Garrosh is now, in terms of individual play after all.
Over all (beeing 11/14 now), with ilvl past 540 it's really easy, without it's not.
DS felt pretty much the same way, seeing how Firelands was nerfed so much, that pretty much everyone had all bosses besides Ragnaros down on hc, and was geared a lot more, than back when you went from T11 into Firelands.
1) Sounds like you guys are ready for HM. Grats?
2) I dunno what your group was like when you started ToT, but if you've been clearing it on at least NM since 4 days into ToT then you're pretty solidly geared for SoO. Plus you have all that raiding experience.
3) It's NM, for a well-organised, experienced group it's supposed to be clearable in one week.