I'm in the ICU at Wilford Hall Medical Center (the hospital on Lackland) and would be happy to help you on your trek.
The advice to gain a year of critical care experience before joining is important as this allows the recruiting folks to bring you in as a 46N3E (46- generic designator for nursing, N-bedside nurse, 3-rough indicator of experience, in this case at least about one year, and E-critical care nurse). Without the 'E' identifier, coming straight in and straight to an ICU slot is difficult (I won't say impossible, but highly improbable). Following this route, you would normally be required to have served 2 years before being selected for school (it's an administrative detail that I can explain further later).
Each year, usually in June, the AF selects candidates to attend CRNA school either here in SA or at the Uniformed Services University of the Health Sciences in Bethesda, Maryland. The application packet includes the standard transcripts/GPA, GRE scores, and copies of annual Officer Performance Reports. GPA and scores are roughly equivalent to what civilian schools require. Some years there is a long list of alternate selectees, and some years (like last) there is a 'Supplemental Call for Candidates' i.e. 'hey, we didn't get enough applications!'.
Since I gather that you are already speaking with a Health Professions Recruiter, you might ask him to sponsor a trip to an AF hospital, hopefully here at Lackland, so that you may see first hand what we have to offer. At that time you can also speak with some CRNAs that have gone the AF sponsored route and other folks that are applying to school this year or next.
If you decide to come straight in without outside critical care experience, your likely assignment will be on a traditional nursing floor, which is the norm in the AF due to our mission: caring for large numbers of casualties during wartime. Nothing sharpens your mass-cal skills like a very busy day on med-surg. If you scoff or giggle, then you haven't shared my experience, and I am speaking from experience on both points. Thus, med-surge experience is important, though not mandatory. If you start on floor you wouldn't expect to move to a unit for about 2 years. During those 2 years you will have the opportunity to accomplish TNCC, ACLS, PALS, etc free (though most likely on your 'off days'.. see my post under Air Force vs Civilian nursing for more info). You will also likely get a chance to travel to a very sunny location for about 3 months.
If you have more questions, or are able to arrange a trip down, PM me and I'll help you and your recruiter set up a tour.