While I have a Broker license, I've don't do any buy/sell transactions.

I have it under contract and the closing is supposed to be by the beginning of November because of some delays with the title company.

If you have a decent equity position you can do a HELOC on the property to build the ADU.

Its sad that doing a "lipstick on a pig" remodel is more advantageous and buyers dont see the cost over years(foundation , electrical, plumbing, etc) issues alot of times when buying. 

You can use the website affordablehousing.com to see the estimated rent for that type of property and location, but it is just a rough estimate. 

They've mandated its demolition but have allowed me to build an even larger addition (500 sq ft).The city is requesting building plans for this new addition.

It's not just about the numbers – it's about creating win-win scenarios where both parties can sleep well at night.3 principles I've learned after 4 years in real estate investing:1) Transparency builds trust. 

Does it matter if it is an LLC or S-Corp?

How did you find this deal and how did you negotiate it?

So, the EXACT thing you think this prospective tenant MIGHT do, is what YOU YOURSELF ACTUALLY WOULD BE DOING!