@Austin Bright - In Texas, if the seller has an inspection report, received or purchased by them, within the last four years, they are required to share it with any prospective buyers. If the previous would-be buyers shared their inspection report or information regarding any major issues or repairs needed on the duplex, the sellers are required to disclose that information to you. In practice, this is very difficult to enforce, and comes down to honesty, transparency and ethics. But you and your agent would be perfectly reasonable to request one from the seller. And if your agent is unaware of this or doesn't want to ask, consider finding another agent in your area who can help act in your best interest.
Do you have a lender yet who you've discussed 203k renovation loans with? They do sound good, but can be challenging. First of all you have to outsource the work, you can't do it yourself. They don't cover structural corrections (foundation, etc). You are limited in the number of contractors you can hire (not usually an issue if you vet your hires). There are different allowances for the FHA 203(k) and the standard 203(k) and the VA 203(k) - some allow appliances, some allow fences, some require a HUD consultant.
If you want a recommendation for a lender who handles these loans, let me know. The folks at SWBC will come alongside you throughout the renovation process and have a database of contractors they've already vetted and approved.
Regarding appraisals, most 203(k) lenders will appraise based on the ARV of the property, so that at least works in your favor :-)
Good luck!