Top 10 CS undergrad. 1.5 years research experience and 1.5 years industry experience

For the USC PhD AD below, do you have any interview earlier? Or were you informed for acceptance earlier and just got the official letter today?

For the Columbia PhD rejections post below, do you submit the new SOP and get the rejections from MS too? Or do you just reject from the PhD program and have no interest in applying MS?

Waitlisted by Amy. They will roll out 1st round of admits in 1-2 days.

On contacting about MS decisions: "The admissions committee is currently reviewing the applications. We will notify applicants of our decision between March thru May of 2015."

Terse response on contacting them about MS decisions: "You should hear from us before April 15."

Is it okay and legal to accept a later offer (e.g came after April 15) with funding, despite having previously accepted an offer (without funding) from a university before April 15. Thanks.

Waterloo undergrad, already accepted the offer from Waterloo

Non CS major, 2 years Software Engineer, 3 classes at Columbia for Masters but taken as Post Bac, 0 papers

Accepted the admission

I got admission from University of Florida and made my decission ,so this is not important for me,at all.

Contacted them, and they told PhD decisions has been made ...

One paper first author

One IEEE conference paper (second author). One journal paper (first author). UG degree in CS and applied math from a not well known US school.