I have a property in Woodstock but used my London agent for my property.
Do you know the city and not the rental scene or are you going in totally cold?
I can try and answer some of your questions based on my experiences and ask a few locals I know for agent references if you like but I am not sure there are many agents out there that 'specialize' in multi-family. I do know that the guy who owns the ComFree franchise has a couple of rentals of his own.
We have a RE meetup next wednesday here in London if you want to come out and see if any of the other know Woodstock.