Our first 5W was a 1987 Wilderness Yukon 24. Many happy memories there, but we've come a long ways since!
I'm not clear what you want to learn about it. You need to dig into the plumbing and find the ruptured lines - may be just one or maybe a lot. It's mostly trial and error. The lines are primarily under the floor and cabinets, but obviously they go up to reach sinks, show, etc. as well. As for the fridge, you need to measure the available space and start shopping online for one that will fit in the hole. If you will have electric hook-ups where you park, consider a small residential model, e.g. a dorm or apartment size unit. Much less expensive than an RV fridge and a better fridge as well.
The actual model designation doesn't make much difference. You can't order parts based on it or anything else specific to a trailer model. If the decal just says "Wilderness", that's what it is, If it adds the word YUKON or CIMMARON, then that is the model. See the NADA RV Guide for a list of 1987 models:
1987 Wilderness Price, 1987 Wilderness Values & 1987 Wilderness Specs | NADAguides
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL