You are better off buying this as a normal purchase or getting cash to cover the rest of the purchase.

My guess is that you will be better off just paying a builder their normal profit on the construction than with a 50/50 profit split arrangement. 

If I can get a tenant with 3X the rent, credit of 600 or better and clean rental history then I normally find them to be manageable.

Normally, people open a S Corp instead of an LLC so that they can pull a salary from the S Corp and save on taxes.

These are affected in my simple mind by interest rates and the cost of entry into new home market and there are less specs than normal in some markets for the same reason. 

There are lots of lenders out there that specialize in different things and have different workarounds. by working with the same broker, they'll understand where your priorities lay and since they have a better understanding of your experience, they can push for exceptions that wouldn't normally be approved.I myself am a broker so I may be a bit biased here, but if you do feel that your current broker isn't very good or that they are overcharging you then you can certainly explore other options.

My experience with these auctions is they are normally slow and inefficient because the new owner had inflated price expectations.

A lot of realtors give good ones a bad name but I can also tell you I get people who ask me for off-market some of the time and this is how the convo normally goes: I explain, "sure but I can also show you homes, set you up with the MLS and - NO NO Pete, we only want off-market.

You gambled your investment capital on an internet investment-promoter.

Now it is a more normal market or even a bit depressed as we are arguably in recession.