It needed a new furnace, central air installed, and the rest of the electrical updated.

Electrical is a tough one, but for water you can do an air test. 

You can do multiple refinances at once, but it's got to be with the same lender and at the exact same time and with full disclosure from day 0.Revisit the HELOC at some point in the future when that will be the only ball in the air until the process is done.

Also, for every pet in the home, "you should expect to get 30 fewer days of performance from your air filter" - which adds stress to the system with lack of compliance. 

Possibly thinking of doing it as an Air BNB and off season doing it as a furnished rental. 

The investor developer does not generally pay full market value as there is no money in it for them.So it sounds like you either need to re-tenant it, sell to an end user, or if there is another highest and best use a developer might buy based on dirt value and improved re-development potential with air rights to increase property values. 

Just concerned about how to get central heat/air in the  basement. 

One question to clear the air with your tenant may be to reach out to them and ask what method would be easier for them to catch up on rent until you begin the regular scheme.

Also up in the air is exact timing of rolled over cap gains, with big funds lobbying for 360 days versus the proposed 180; lengthening the construction period beyond the suggested 30 months; and allowing interim profits to be rolled forward.All the same, looks like OZs will be a good alternative to 1031s.

My girlfriend and I recently bought a drone (DJI Mavic Air to be specific).