Priest Lake is a gorgeous area. There is a Priest Lake State Park Facebook page, as well as a lot of other info to be had by Googling the various towns in the area.
As far as crossing into Canada, if you are taking a dog with you, make sure you have up to date verification of its vaccinations. Also check with the Canadian website http://www.inspection.gc.ca/food/information-for-consumers/travellers/what-can-i-bring-into-canada-/eng/1389648337546/1389648516990
To verify what you can and cannot bring in.