I'm dealing with a seller that is driving me up the wall.

Or, do I just assume all wall behind a bathroom wall needs to be textured?

Once you open up those walls you never know what you will find.Things like a roof or termite damage could cost you thousands of dollars to repair and would likely eat most of that 10k.You really have to know your market well and what type of upgrades the buyers are looking for in that particular area. 

This would be a legal issue, I would suggest the quit claim if executed, would be in front of an attorney of your choice, notarized, sealed, and copy of the file kept on his file depository, your local UPS Notary will not retain a copy of the wuit claim.

Get into the attics and pop off some cover plates on exterior walls to see what the wiring is like.

Also, if you have hot air duct work floor mounted or close to the floor wall mounted, check for the duct covers securely installed.

@Mindy Jensen I was asking the inspector for a full inspection on a 2500sq foot house that had no sinks, light fixtures, hot water heaters, multiple holes in the walls ect.

I know you are speaking of a SFH, but I refuse to purchase any multi-family dwelling if there is mold requiring demolition (dry wall, plumbing). 

I tend to think it best to stay away from HOA situations.I literally ran into a buddy today who has a condo in an HOA and is going through a nightmare scenario of a roof leak that has destroyed a couple interior walls and is very costly to repair.  

No attorney or CPA, no matter how good, can provide you actionable and reliable information in a setting such as this.I hope this serves as a good starting point for you to do further research and / or retain a professional to assist you.