If you get a freezer you also have to get a temperature control like a Ranco or Johnson Control. This controls the freezer to allow higher temps than "Frozen". I serve my kegs in the mid 30's.
And to answer your other question, it's all personal preference. If you're not blessed with height as some of us are then a chest freezer may not be your friend...reaching in and lifting out the keg could be a chore as well as cleaning. I prefer a freezer so I don't have to jockey around kegs so much just to get the one in the back out. I just reach in and pull whichever one I want straight out.