I work for a Big 4 firm and will be attending Kellogg this fall. I actually think CPA/Big 4 is relatively neutral to adcoms. It definitely demonstrates that you've got good quantitative skills, but raises questions around teamwork, leadership and other interpersonal skills. I think what's most important is what snipertrader said a few posts back - it's what *you* bring to the table that counts most. If you're an auditor and have just done audits your whole career, it's going to be harder to distinguish yourself from the other auditors applying. Try and branch out, volunteer for projects in other areas, get involved outside of work, look for experiences that show that you're more than just a number-crunching beancounter.
As for career switching, I am planning to go into product management or GM in pharma/biotech post graduation so it's definitely possible to get accepted as a CPA who wants a major career shift. As for whether CPA is seen as a positive by recruiters, you'll have to ask me next year.
Last, in terms of schools I don't think any schools are CPA-friendly or CPA-unfriendly. There's a lot more to admissions than that. Again, it comes down to what you bring to the table - your skills, your personality and how well those fit with the school - that matter, not the letters after your name.
I think those were most of the questions you guys raised, but if you have more feel free to post them or PM me.