What are some of the best questions to ask a seller with a tenant occupied unit?

  $80k sounds pretty high to me even to tear-down-rebuild, which is probably an excessive approach just to make parts align right.The dividing line between owner-occupiers and investors in buying and selling decisions is the investor approach is the numbers. 

@Ben Joseph the proper policy is you need is a Non Owner Occupied Rental Dwelling policy, commonly know as a Landlord policy.You are correct in a Rental Dwelling policy will usually have Liability as part of the policy.

I’ll occupy one of the commercial units and it will help me in my business as well 

So I've considered paying a friend say $50 a tour for getting a vacant unit leased and hiring contractors for repairs that come up when the unit is occupied since the tenant can let them in.

My state being one of them, Oregon.They give you $17,500 back Credit score must be 640 And above 1yr owner occupied. 

Assuming you're getting an owner occupied rate, I would say that's very competitive.

If you are looking to do 1 unit investment property with Conventional/Fannie/Freddie the down payment is 15% and if you want to do a 2-4 unit the down payment is 25%.Another option for you is to get a 2-4 unit Owner occupied FHA loan for 3.5% down.

I don’t think you’ll get a permit to build any non occupied structure, by itself, on the empty lot. 

That will be enough for your lender to proceed.I bought a fully occupied duplex and simply provided the underwriter a 60 day notice from the seller to tenant #1 that was 60 days after closing.