My impression is that there aren't very many veterinarians or vet students on the forum, but I might be wrong. Someone else can answer this better than I can, but I'm not sure they're on this site
That being said, I'm not a vet student, but my sister just graduated from vet school in May of 2010, and I lived with her and 2 other vet students for the last 3 years of their DVM program. First of all, congratulations to your daughter! Getting into vet school is a huge accomplishment, and getting accepted to 2 and wait listed at 2 is pretty awesome.
My sister went to vet school out of state because that was her only option. She got good financial aid, was on the Dean's list every semester, and won several small to medium-sized scholarships, and in the end, the amount of debt she graduated with is almost crippling. She will be paying back $2,000 a month for more than a decade. On a newly graduated vet's salary, that is very steep. She's not sorry she did it because it's her passion, but I suspect that if she could go back in time and erase $80k of that debt, she would do it in a heartbeat.
Only your daughter can know which choice is the right one, but if it were me and I was only somewhat more interested in the out-of-state school, I'd go to the in-state school. $80k is a lot of money, and even with Stafford loans, she'll be adding tens of thousands of dollars in interest to that amount.
But that's just my two cents, having witnessed the financial pain my sister and my best friends are currently suffering as recent vet school grads.
Regarding the wait lists, has she tried asking the 2 schools where she falls on the list? I know for a fact that some vet schools will tell you if you are in their top few choices, and a polite inquiry won't hurt her even if they refuse to tell her where she's ranked.
I'm afraid I don't know the answers to your other questions, but I think she should probably be very careful and do some more research before she accepts an offer with plans to (possibly) back out to attend another school. In some fields, that can cause serious problems, and the community of vet students and schools is pretty tight knit and really not that big. There might be a way to do it completely above board and responsibly, I don't know, but I'd make sure first! Which is what you were trying to do by posting this, I know...I'm sorry I couldn't help more.
Again, congrats, and good luck to her!