There are places in Biddeford that are (very) nice; and like EVERYWHERE else, there are places in every single town here that are definitely not so nice. I also have 2 kids, and we found purchasing a home MUCH cheaper than renting. Problem with renting a house in the area is many of them are "seasonal" rentals -- you only have them from Labor Day until Memorial Day (there are exceptions that are year-round). I caution you about realtors here: the realtor fees are OUT-FREEKIN'-RAGEOUS. Realtor.com and FSBO.com were my best friends when looking for a place to buy.
Biddeford and Saco both have relatively low crime rates... with a few exceptions in certain categories. This information should be readily available on the web (I forget where I looked it up).
As for school systems, the testing results from maine education admin (or something) are also available online. I was appalled by the results, but they are rather similar for many school systems. Best advice: go talk to the schools. I found them to be quite forthcoming about their shortcomings and also forthcoming about programs to challenge advanced children. The biggest problem schools have here is that many parents don't want to be involved, and the kids are involved in too much other stuff to devote appropriate time to homework. Same problem everywhere else is having.
Overall, I'd wait to see if you actually choose to go to UNE before you worry about housing. The housing bubble here is bursting, which will only work to your advantage, and if you end up choosing UNE (and they choose you), I'd recommend taking several weekends, or an entire week if you have it, to come up, drive around, explore the area, and look at housing then.
Good luck at your interview. I am very happy with my choice to attend UNE... but I'm also quite aware of the shortcomings for families. There are shortcomings no matter where you go, and no place will be absolutely idyllic for an entire family. There will always be worries, explorations, and extra time for plans to make when you have more than yourself in tow. Overall, Biddeford is, so far, a really great place got my kids and my husband. And Portland really isn't that far away for weekend trips with the family - only 20 minutes or so. I'd rather drive up there once a week than drive down to school every single day. Don't forget -- during things like anatomy you may want/need to spend extra time in lab, which would entail making the drive more than 5x/week.
You can drive yourself nuts worrying about stuff too far in advance. One thing at a time. Personally I found worrying about the interview MORE than enough!
Hope I didn't scare you too much here. Back up: one thing at a time, and good luck at your interview!!!!!!!