I am a multiage teacher and I have seen both wonderful and horrid examples of this fabulous style of teaching. My suggestion would be to ask the potential teachers a few questions, such as the following. I, personally would be listening for keywords such as those I put in parnethesis.
Describe your program. (Developmentally appropriate, based on a cintinuum of learning)
How will the kids be instructed in Reading? (Guided Reading, Literacy Centers)
How are the children grouped for instruction? (flexible grouping based on ability and skill needs)
How will you enrich the high (again, flexible grouping and developmental continuum)
What is the difference between a multiage class and a combo class or split class? (MA is on a developmental continuum where kids stay together with the teacher for at least two years, a split or combo class is two grades, taught seperately by the same teacher -usually due to enrollment numbers and NOT by teacher choice)
Visit my classroom webpage if you want more info on Multiage - I have downloadable info if you want to research further! (teacherweb.com/ap/andersenelementary/cynthiamiller
HTH! Good luck!
Cindy