What is a typical finders fee (%, flat, profit, etc.)?  

You also may want to include expenses for a dumpster, landscaping and snow removal (if applicable given your weather).Growth assumptions are likely skewing the numbers as well as you have expenses and appreciation as flat with income increasing 5% annually. 

being a west coast flyer we look out for big rocks.. out there in flat land country I was dogging radio towers 2 and 3k feet in the air  … different experience.. of course we are used to cruising much higher than a lot of the guys I talk to that fly GA out east.. 

Instead it's a vehicle where you can park your excess cash from your W-2 or business, but the first step is to create that excess cash.

Property Management reserves the right to reject any application due to any one or a combination ofthe following:• False, incomplete or insufficient application information;• Credit score 550 or less,• Credit showing delinquent accounts with collection balances due; foreclosures, bankruptcies, liens againstthe applicant for taxes or child support, judgments against the applicant for evictions or property damage;• Rental histories showing excessive late payment, NSF checks, property damage, lease violations;• Income shortages less than the required monthly amount;• Criminal histories showing felonies, misdemeanors, DWIs, DUIs, theft by check, domestic violenceHaving something like this will help you eliminate "gut feeling" criteria and ensure you are treating all to the same standards of qualification. 

If it's a low $ value deal it's unlikely you'll be able to negotiate enough into the deal to cover the work.A flat water/sewer fee may be acceptable in your market.

Enclose the garage or add space, and then add an ADU in the far back (granny flat).

Since it seems like you are giving back the excess money

A PIA gets a higher increase, it does not have to be excessive just a message. 

The other way is to agree on a flat fee.