The lender is stating the following: "we would require a mortgage on the lot in the amount of $90,000.00 when combined with your $50,000.00 deposit would be $140,000.00 down payment apx a 20 percent down payment"Is he saying I need to find another $90,000, or that he will act as the mortgagee on that portion as well? 

In my experience, once you really get rolling, aside from contractors, a good CPA and attorney are vital.

We use a product called Vital Oxide in our flips to neutralize odor and disinfect.

Both the liability portion of the renters insurance (which your renter will pay) and the umbrella policy are generally quite reasonable, but I am sure that varies also with where you live and own property.

If they don't complete the deal in 2 years, there is no messiness as their option period simply expires and the purchase portion of the deal is done.

My question is, is there anything more I need to do to (i.e. issue a formal written notice of lease violation) in order to prepare for the possibility of keeping a portion of their security deposit to pay for eliminating the odor? 

I am trying to see if the numbers still make sense to do so after financing the equity portion that I would owe my sister.Any thoughts on how I can finance the $140K in equity I would owe my sister?

I couldn't just use a portion of the taxable gain to purchase a less expensive property?

Would also cover a portion of any repairs to utility hookups if needed.

VA loans require a significant portion of the loan term, while conventional loans typically require moving in within 60 days.