Pay for the basement reno out of your regular savings as the build progresses and as you have the money saved.   

There are specific policies for Vacant properties that may provide more coverage for the building than a regular policy once the vacancy provisions kick in. 

I do mailers (although not as consistently as I should) and get returned mail back regularly.  

If you plan to build anything there, this could result in some fairly high annual flood insurance costs and/or if flooding is a regular occurrence, it could get in the way of whatever other activity you plan to do on the property.What are the required building setbacks for the property?

However if you want it to look like a regular house in the interior or exterior or both then it is not worth it.

I had my contractor that I work with regularly take a look at it and he's saying its a gut job which will cost 220k.

When I kept telling her that she wouldn't be able to retire until 67 if we didn't find a way to make money other than our regular jobs she started to listen (she's 56 now).

Most regular GCs won't even know how to use this tool. 

Real estate is not like the regular stock and bond market.

I usually dump all my OH like a regular project and dump everything there then split them at year end to get my p&l.