Hey Kevin,
I was going to ask if it was manufactured or modular. There is a significantly different building code for the two.
Why is the seller paying for anything over $1000 that needs to be remediated? I've never heard of that and the seller's agent would be a bad agent if there was a stipulation put into the contract that allowed that. You get a roofer out, siding buy, deck guy, plumber, electrician (you get the idea), they can all find work that needs to be done to a 20 year old home. If you do have a stip in the contract that forces the seller to pay for anything over $1,000, please share it as I'd love to see it.
On the inspector, you should be able to have as many as you'd like - especially with it being vacant. I'm not sure if it would be worth the money though. It's around $400 (give or take a hundred) where I am for a SFR.
As far as your outs, I'm not familiar with WI real estate contracts. Do you have a due diligence period?
As for the mold smell - it's probably super musty if it's been sealed up for two years. Of course, have experts test if you feel there's a safety concern. I would expect the property to smell though. If there are no soft spots in the bathrooms/kitchen, then you're a step ahead of the game. I think almost every manufactured home (also called mobile homes even though it's not totally accurate) I've been in that's more than a few years old has soft spots in the floor. Maybe they took care of all that with the roof work.
Just to double-check, does your lender know you're buying a manufactured home? They don't get the same rates/terms as a stick built in most cases.
Ask your agent if you have a due diligence period, when it ends, and for what reasons you can get out of the contract if you want to. Ask your agent what other contingencies you have (like financing, appraisal, etc). This will let you know all the ways you can get out. That being said, how much is your earnest money? That's what you're risking if you break the contract with fault and I'm hoping that knowing that offers some comfort. I'm guessing it's less than all your inspections. :)
Also, it sounds like you may have some nerves and are wanting to get out of the contract. Run the numbers and reassure yourself. It sounds like you got lucky to get this one under contract. :) It's totally normal to feel nervous when you get a property under contract but don't let those nerves make you step away from a great deal (assuming it is). :)