Any lender close to $100k mark should/will want an appraisal. If they do not, then chalk that up in the "hell yeah!/ROH TAHDE" Column.
It having a structure on it, it definitely will need to be inspected, but be ready for a bank AND CU to balk at that structure being a "home" for purposes of mortgage. The bank I work at, along with the Credit Union I do lots of personal business with... Neither would so much as entertain a pole-barn as a conventional mortgage. (So I'm renting until I find raw land to build with cash).
His tax records could be any number of things, it may be how much he has in lein on the property so the tax assessor uses that number mark to tax him, or it could be the value that he has used in years passed, so the tax assessor uses that value. Who knows. You can actually bring paperwork to the court house and get your taxes lowered if you can show the value to be lower. May take half a dozen trips, but it can be done.
Good luck to you! Cause it looks fuggin AWESOME! Hope it works out. Wish I could find that building on a 5 acre parcel over here... South of bham where I need it to be... They keep popping up in West Jefferson and near Cullman, not near where I need it to be.