First, I'm no expert, but this is my thought. First, never, never load anything on a TT bumper. They are weak and flimsy....a gen and firewood weighs more than you'd think. Your mistake there. DH hates the scissors jacks that we have on our Rockwood 2604 and pretty much thinks they are a POS. We are looking for the long arm with the foot that our HTT had in hopes of making a change. However, the additional weight of the gen + firewood could certainly have make a problem with the stabs. I cannot imagine that the additional weight would have caused the problem with the door, but suppose it's possible.
I'm a bit confused about the popping sound while filling the FW tank....more info? Hard to imagine that you could have filled and filled and filled and not noticed the amount of water going into the FW tank, but guess it's possible to have leaked out into the undercarriage area.
We are on our second FR trailer, first an '07 ROO 23SS and now our Ultra Lite 2604 without issues. I'm sorry it appears you got one that was built on a Monday or Friday and should have been painted a lemon yellow, but it happens to every manufacturer.
So....document everything. What you said, what they said. Keep every piece of paperwork. I'm concerned that your dealer is trying to brush you off and that's not gonna work. If you need to, contact FR at the location shown as the build facility on the yellow sticker on the street side....the ones with all the weights. Tell them what you've told us. Even the part about the gen + firewood, which may end up biting you, but be honest. Ask for their help.
Since it's the middle of the season here, closer to the end of the season in MT, give them the opportunity to make it right over the winter. At least you won't have to broom the snow off. It appears to me that you made some mistakes, they made some mistakes, the dealer is trying to brush it off and you're stuck in the middle. First thing you need to do is get that gen + firewood OFF that bumper and keep it off. The other things, such as water, are not your problem as I see it. The weight/stabs/door might be. But let the factory, if necessary have a go at it.
Sorry you have had to deal with this mess. Camping is certainly less enjoyable with one thing after another coming along. Maybe next season will be perfect. But keep the gen + firewood OFF!