Unless something changes dramatically (I don't think it will), calls start to go out to Asia late night/early morning on Tuesday/Wednedsday. Then calls go out to the US all day on Wednedsday. I haven't heard of anyone getting calls earlier. There were false rumors of early calls back in Round 1, but I think Derrick has hewed pretty closely to the above schedule in the past. I can't comment on application volume, etc., because Derrick specifically told us that info wouldn't be released until matriculation.
I think there were less than 5 (total, not percent) college seniors at Admit Weekend out of total attendance ~150. A _lot_ of people were M/B/B consultants, PE, VC/entrepreneurship, or Google/Microsoft with 2-4 years experience, so they fall in the range you mentioned. Yeah, a lot fit that standard type of profile but they were a fair number of oddballs- Peace Corps veterans, teachers, etc. I was probably among the oddest
.
I think that profile is, like it or not, a mark of "pedigree" that a lot of schools go for. (Please, no one start a flame war... I'm not trying to turn this into B-week.) Based on my interactions with other prospective students, I really do think that Stanford looks within that group for people with a sense of idealism and a desire to positively impact the world. This inevitably sounds wishy-washy and lame, but I'm being intentionally vague here. I don't feel comfortable providing examples of other people's goals in a public forum.
I'm sorry my answer to that last part is so unhelpful
. Let me know if you have specific questions in that area, and I'll do my best to answer them.
As an aside, I've spent way too much time on gmatclub today... clearly, my GF's on call