downspouts pouring out water next to foundation, negative slope of outside soil or concrete, clogged gutters etc...

Auto helps for sure but not the end all be all.And Detroit has no bearing its BMW Mercedes and Volvo.. additionally its much like SF  its a peninsula surrounded by water on 3 sides there is only so much land.its an Awesome city and place.. and I thankful one of the top flight TV Guru's turned me on to it 4 years ago !!! 

That number has no bearing on California where 150k is not a high number.

Ask your realtor to check if expansive soils are common in the area. 

As to permits & starting at light demo not removing studs is fine but depending on if the wall is load bearing (and how you inspector wants you to verify, your contractor knows to need a structural engineer have been answers ibhave gotten) is what permits will be needed have a good idea of what you want when finished before moving walls etc Best of luck!.

Other situation specific items that would cause you to change your intent from long term to short term (one of my clients had a bear take up residence at the trash can so he decided to sell early and 1031!!)

Pistons, rings, bearings and the top end.

We are in a real estate bear market now and for human property owners, it's better to have more institutional buyers rather than fewer. 

Bear in mind, I'm not saying you've got to start flipping or land speculating or anything.If you're hell bent on avoiding risk, then I would probably focus on growing my income at my job like crazy, since you're money won't be working that hard for you.

@Christopher J Lemmon In my area, where the soil tends to be sandy and will drain well, we budget $35,000 and hope for $20,000 - $25,000.It's hindsight now, but when writing an offer, I always include a contingency that lets the buyer either get a price reduction or cancel the sale based on the outcome of the septic inspection.