Should I omit some of my qualifications in my application materials to "surprise" with during an interview?
No.


How will you know exactly what's "just enough to pass the first selection round"? You won't. You can't.
Don't "surprise" by withholding helpful information. I believe most people find it annoying and inconsiderate when someone deliberately withholds information that they need in order to do their job (which is what you are proposing to do to the selection committee).
It's harder to change someone's opinion of you than it is to confirm it. Even if you manage to get an interview using this strategy, convincing the interviewer that the candidate he thought was mediocre is really exceptional is more difficult than making him think, "This student is just as exceptional in person as I thought he would be!" (Also see: confirmation bias)
Presenting yourself badly on paper can lead the committee to think that you don't know how to present yourself well, or didn't bother to find out how, or didn't care enough to put effort into your application. These are not qualities that people look for in an applicant.