I don't think that I'd have a 3.98 mba gpa without having gone to pit, but who knows.
I am quite confident that you would have done very well with or without going to PIT (side note: I heard in the name of the founder of PIT - would have and should have is apikorsus). And if you would have had 3.97, or 3.89, or any other mark, do you really think it could have made a difference?
Your kids are still young, so you might have not been exposed to
this, but I think there's an important message about trusting Hashem embedded in that movie (2:40 in the trailer), however there are countless letters, sichos, etc. regarding בטחון and where one's פרנסה comes from. Not the least of which is a directive the Rebbe has given many, which is to learn (or read) שער הבטחון. I would suggest that it should be a prerequisite to positing on this subject.
As for חינוך על טהרת הקודש and excluding secular studies, IMHO those are actually two separate (if somewhat peripherally connected) issue.
I would suggest that חינוך על טהרת הקודש is more of an overall approach and attitude, that permeates everything. To put it the way I suggested to several principles in Crown Heights years ago: The Rebbe suggested that public schools should begin with a moment of silence, why shouldn't our schools begin with the same (though since we aren't restricted by US law, it doesn't need to be silent). To put this in other words, I suggest that חינוך על טהרת הקודש starts with the goal in mind, of imbuing the students with an acknowledgement (at the very least) of דעת עליון that אלקות בפשיטות ועולמות בהתחדשות! As long as everything is permeated with such an attitude, learning math and science (from an appropriate curriculum) could be (and
is IMHO) על טהרת הקודש! (my SIL actually created a math curriculum על טהרת הקודש that goes up to sixth grade, it is used by some schools and is available in Hebrew and in Yiddish).
I think that avoiding secular studies (assuming that they are kosher) is a separate issue. To understand the Rebbe's perspective on this, I think we should look no further than the Rebbe's directives regarding preparing a bar-mitzvah boy for
layning. As far as I understand the Rebbe's position on this, the Rebbe considers this a waste of precious time, that should rather be spent on learning more important things. IINM the Rebbe expects that by the time a child turns Bar-Mitzva, the child should know the entire Kitzur Shulchan Oruch (except for halochos that aren't relevant to unmarried people). There are only that many hours a child spends in school, the time needs to be allocated by priorities, and secular studies cannot take priority over what's really important.
As for the language, I think it is also quite clear that the Rebbe expects kids to be taught
in their own language. However, what should one do when the kids have no language (as is sometimes said, that CH kids are illiterate in 3 languages)? I think that problem stems from lack of consistency. If kids were taught in one language from an early age, they would have no problem learning in that language. The problem is that they are taught in a mixture of languages, and often by teachers lacking language skills. How should language skill be acquired? I think the answer to that lies
starting here (read the entire thing, it's less than 4 pages long).
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