Understand the fees involved and calculate the total cost for an entire year of management so you can compare the different managers.

They suggested while the property is vacant it is easier to repair, which costs 10-15k. 

I do not have much knowledge on real estate but I am the hitting  books: BRRRR by David Greene, Estimating Rehab cost by J.Scott, Investing real estate with no/low money down by Brandon Turner and finally, Rental property investing by Brandon Turner.Outside of real estate, I enjoy swimming, bike riding, watching anime, playing video games and interests in the stock/house market.Excited to learn and connect with you all!

But when I got my first bill from the attorney for 3000K+ I started to worry about how high legal costs could get even if they buyers dont win.

Not aware of how construction cost are looking in Milwaukee, but I'd talk to a couple of contractors/developers in the area.

My $10k example was admittedly unrealistic.However, by way of further background, @Dustin Heiner wrote an excellent article on this topic on his website masterpassiveincome.com titled "What to Do When A Buyer Backs Out From An Assignment Of Contract".In it he suggests a scenario where the assignee decides not to proceed, perhaps after discovering a big ticket repair item that would cost significantly more than the portion of the assignment fee held in escrow. 

Cost segregation is a popular tax deferral strategy and there is often confusion as to the difference between bonus depreciation and reclassification.Bonus DepreciationBonus depreciation is a tax incentive that allows a business to immediately deduct a large percentage of the purchase price of eligible assets, such as washers and dryers, rather than write them off over the "useful life" of that asset.

recessed/sheetrock is a low cost, no brainer improvement that sells.

I’d just have to figure out how to come up with rehab costs, and learn about seller financing a bit more within a short time frame.

I'll sound like a broken record, but STRs definitely hold a lot of hidden costs and regulations.