I will only be using this license to assist with flipping - no interest in being a real estate agent otherwise - so I'd prefer to work under a broker that respects my intentions, doesn't require additional work, doesn't charge astronomical fees, etc...  

Only difference is they finished the basement and we won't, but from what I've read, a finished basement will only impact the ARV by 10% max on average.We also don't want to go too crazy with the changes b/c we don't want an astronomical renovation bill.

They wanted an astronomical amount of money including decades of late fees, interest and of course the original principle.

I'm remind of the old Twilight Zone episode where the lonely guy buys a love potion for cheap, like $10.He was impressed at the exceptional value and it's powerful effect on his love interest, who doted on him and made him the object if her desire round the clock.I don't recall what the antidote cost him, but he gladly paid the old shopkeeper the astronomical price to get 'her' out of his life.Perhaps the note could be "gifted" to a competiting note buyer?

The returns are astronomical at the end of the day. 

Upgrading the HVAC system is something to help increase the value of the home (Not an astronomical number) and can be marketed as a Green renovated home, Not to mention its something you can tell to potential buyers with one less thing for them to worry about. 

I have been reading all the information I can get my hands on (surprisingly, there is an astronomical amount- for free).

Your analysis looks good, but a few notes:Without knowing anything about Chicago, the insurance numbers and taxes especially look astronomically high.

But in talking with this realtor friend of mine, he was saying if you're gonna upgrade your home, do it now, because if you decide to upgrade in say 3 to 5 years, the prices you'll end up paying will be astronomical.

Rents therefore are also astronomical.