Some CA residency programs have GPA cutoffs (usually around 3.0). Thus you don't necessarily need straight As, but you need to meet the cutoff.
Many CA residency programs have oral and/or written exams. The oral part is not necessarily called an exam, but from what I've heard it sure mimics what we had in school (our school has oral exams). These grilling sessions test your clinical knowledge as well as your thought process, as you are not expected to always know the answer to everything. However, the clinical knowledge portion is vital, so no matter what school you attend, you need to prepare for this.
It seems like the academic medical centers like a smattering of out-of-state students to get varied viewpoints. I think the preference for a certain school depends on the facility. I have encountered places that have an entirely local cohort of residents (though perhaps the entire application pool was local) to academic medical centers that have a mix.