New Trailer, New Member

Well after a little over a month on the forum and a ton of research I'm starting my build. I bought a 6x12 small v-nose used. Got it off an older guy that used it to transport his motorcycle in, but only used it a few times. My plan is to turn it into a home for my wife and I for up to a year. We are going to take a year before we have kids to travel around the US. The tow vehicle is a Nissan Frontier 2007 V6 4x4 115xxx miles. We are in the insulation/window install stage right now. Order my windows today, 24x15 and a 30x20, should ship tomorrow. The first questions I have are about a vapor barrier and walls.... Do I need one? Does it need to be on the skin side as well as the inside side of the insulation? Has anyone tried the liquid nails method of attaching the walls to the studs?