Since the lower unit is already small I am not a huge fan of this since the heaters sit on the wall and take away from living space but it seems like the most cost effective solution I've found so far.

You should get input from local agents on what rental rates you can achieve in light of the slightly unusual location and you may want to factor in some additional vacancy if you want to be conservative.

Added that to $5700 gained from six months of saving + extra earning and you've achieved over 20k new money by this time next year.

The issue I have with IRR, is that i don't (yet) have an estimated time frame for exit and am not really looking to 'flip' things..further, is there a simple way to compare varying conditions of unit?

There are numerous successful syndicators that project near 20% annual return and have a history of achieving better than projected.  

I know I’m getting the newbie platform SEO boost, but still - Superhost is easily achievable at the first review period if you make a fairly average effort, and it’s not actually that hard to separate yourself from the pack on Airbnb if you just do everything you need to be doing to run a good businessGood luck hunting to everyone!

.. the unit is currently fully occupied.

You've successfully closed the deal, and it's time to start this exciting new chapter.ConclusionNegotiating in real estate is an intricate dance that requires preparation, strategy, and effective communication.By taking the right actions and understanding the dynamics of negotiation, sellers can increase their chances of achieving their goals and securing a favorable deal.In the world of real estate, knowledge and skill are your allies on the path to a successful negotiation.

For example:  Is the advertised NOI of $36,000 achievable?  

you'll need a portfolio or commercial lender who is typically a local community bank or credit union since conventional max cash out on 2-4 unit is 70% LTV.In WA state I know commercial lenders who go to 80% LTV on cash out with 30 year amortization, 15 year term, 5 year fixed, adjustable every 5, with 1 point in loan cost.