My wife is also a realtor with 8 years of experience, and together we currently own 10 doors.

I have year of 7 years of experience with drywall, and paint work so that helped me out a ton.

You could leverage your experience while they can bring the capital. 

So overall experience of your QI to work in a number of markets and locations is really the key. 

In my experience, the best thing to do is warn people over and over again.

In my experience, your level of wealth that you can handle is based on your mindset.

And the fact that your post had at least three votes for it when I posted this shows that there are lots of other people who would probably be losing in PA under those same assumptions that just happen to be FALSE in Pennsylvania.Pennsylvania has some rather complicated rules when it comes to tax sales; the particular type of sale that the OP purchased at is one that does not divest any liens; it simply changes the party that is the owner, with the new owner taking title subject to all liens and encumbrances of record.With tax sales, the buyer must be aware of all the local rules under which the tax sale is being conducted, because the rules vary all over the place.Now, what the OP seems to have failed to do in his research was to cross index the recordings at the county recorder; the "missed" mortgage would have showed up on a search by parcel number if that sort of cross check was done (and assuming all indexed documents at the recorder are properly indexed of course - I have seen mistakes made attaching a document to the wrong parcel).

It seems that most of the BP influencers I have seen over the years have stepped into MF syndication with varying results.

I believe this is what they call a pier and beam foundation which I have no experience with so I have no idea what it would cost to fix. 

Most lenders will vary how aggressive they will get based on the experience of the operator (you), but I don't know any that will lender to someone who's never done a spec build like you're contemplating.