Well, I know a fuge is short for "refugium". An area that has escaped change. Basically its a place for your pods to live and grow without being vunerable to powerheads and fish, etc.
Also its where many would recommend putting nitrate eating plants. It can be a tank or some people use plastic containers.
Another popular thing is to have your water cycle from your main tank through your fuge back to tank. Known as a sump/fuge.. do a search on the message board for sump fuge to get a better understanding of all that. I dont have one yet but im researching a bit. I dont know anything about a wet/dry.