If I were you, I would tell the daughter that spoke to you, "I found out great news. I checked with a real estate attorney and found out that the people that built the porch will be fined, not me. Also, if I have to tear it down or make repairs, I can sue them for all costs, including legal fees. I'm so relieved. It seems that they never properly disclosed their lack of permits on the real estate papers. I'm so glad that you brought all this up. Now I can get the porch fixed up, and they have to pay for it." The family is probably stupid enough to just back off. You don't have to tell them that you don't want to hire an attorney. Let them sweat it out. It seems unlikely that they can fine you. Also, I doubt that the rubbermid shed needs a permit. If there is no foundation, it's moveable. It's no different than parking a car in your yard. It's mobile, not a permanant structure.
By the way, you didn't start the war, you just didn't let the enemy take advantage of you when they started it. As far as the code enforcement people, I doubt that it's appropriate or allowed for a municipal employee to give out information on who made a report. File a formal complaint with the code enforcement office. Make a real stink about it. You didn't start the war, but you are in it now. Surrender is not an option. You either have to win it or have a truce.