First of all, you're still a good candidate for plenty of ACGME Rads programs, specifically community programs. You likely won't get many looks from the top academic programs, but community ACGME is still very attainable for you.
To schedule rotations, I looked up each program I was most interested in, and on their own hospital website they will typically have the contact person to schedule rotations. I simply emailed them in Jan/Feb to schedule rotations anywhere from July-Nov and I had no problems whatsoever. I believe I may have called a couple as well and scheduled the rotation right over the phone. Luckily, none of the programs at which I rotated utilized VSAS for scheduling.
From my current experience, I haven't noticed much of an impact of programs favoring students from their respective school. The biggest advantage these students would have at such programs is the ease of access to rotations and maybe spending some additional time with the programs "off the books". For DO programs, audition rotations are HUGE! I know at Grandview they won't even interview someone who hasn't rotated through unless "they are an ex-Navy Seal with a 700+ COMLEX" (that's a direct quote from a current Grandview resident that obviously isn't meant to be taken literally but just shows how important auditions are for them). Other programs may not have such strict preference for auditioning students (I've received 3 interviews so far from programs that I didn't rotate through and all the programs I have rotated through have offered interviews), but auditioning will never hurt your chances, unless of course you are an over zealous student who likes to correct residents.
As far as my stats, they aren't great. I was close to, but under 600 on both level 1 and 2, and didn't take USMLE. Top 40% of class, mostly High Sat and Honors for 3rd year. I have no research or other radiology experience. Biggest thing is to show interest during 3rd year, spend as much time getting to know radiology residents and attendings as possible (get a couple solid LORs), and do some audition rotations where you're interested. I've also received a few interviews at ACGME programs (I applied to 16 community programs), so definitely keep that in mind and apply broadly.
If you all have any other more specific questions, feel free to PM me and I'll try to get back to you ASAP. Also, check out auntminnie for some great advice and search through their forums; lots of great info!