I'm planning on going to the airshow too as my birthday is in August and my sister lives there. As for the alert helicopter they are based out of the Kalispell Regional Medical Center. Their website is here: A.L.E.R.T. Air Ambulance | Emergency Care | Kalispell Regional Medical Center | Northwest Healthcare, Kalispell, Montana
We do not use the UHF med channels around here the I know of. There are 2 UHF frequencies used for medical; 452.2250 & 457.2250 I believe. Besides the regular VHF State interop medical channels.
Oh and the turbo prop airplane is at the airport I assume, ha ha. That is alert 2 & the ambulance is alert 3. Hope this helps.