Congrats on your pending venture, a new home!
I am a certified Home Inspector and have a few ideas for you.
Actually, there are several items that a good home inspector is going to look at that are not on your list. Keep in mind that an inspector is going to be able to render an opinion on the condition of the systems and structure of the house. Other items should include, chimneys, flashings, gutters, windows, screens, sills, exterior fixtures/lighting, attics, vent fans, proper wiring, GFIs, water heater/temp, heating systems, fireplace dampers, window operation, door operation and weather stripping, step and railing safety, and the list goes on. Extra inspections may include, radon, water, septic systems, wells,or pools.
If you want a good reference and sample checklists, I recommend the book The Complete Book of Home Inspection by Norman Becker, PE. There are several good books out there, but this one is simple and to the point.
When you do find a property that you want to make an offer on, be absolutely sure you include a contingency, or condition of sale, that calls for a professional home inspection, and that the inspection results meet with your approval. In other words, if any discrepancies or findings are in the report, you can get your deposit back and walk, or negotiate with the owner for a reduction in the amount of your offer to professionally repair the problems.
The average cost of an inspection in my area for a home under 4000Sq feet and less than 100 years old is about $350.00. Under no circumstances should you not have a professional inspection and the associated contingencies in your offer to purchase. Once you make an offer, a DIY inspection is not legally enforceable, and you will have no recourse and unable to walk away with a refund of your earnest money deposit.
Sometimes panel manufacturers will have a null breaker slot on top, bottom, and/or both. Even though a double breaker seemingly fits right in like it's supposed to, only one phase will be hot.
A visual inspection of the busbar is one way to tell, or if you have the busbar layout diagram it will show too.
In case this is the problem, simply move the double pole breaker into the proper slot, then put a blank slot filler to cover the exposed parts. If you don't have a blank handy a breaker with nothing on it is fine too.
Best Answer
From what I can see in the fuzzy pic, someone wanted a double-gang outlet where there was a single-gang box. They apparently didn't want to cut the wall at all.
There's probably no concern as far as safety, but pop an outlet tester into it to be sure.