Also, there's a window in the shower with a wood frame.

Replacement of roof in 2008 and windows in the year 2000. 

Also window units are very common in that area as well.

Here is a list of the work that needs to be done:Total sqft: 15751st floor: 9302nd floor: 645Lot dimension is 100'x150'Side driveway with access on the frontBack detached garage 1 stall access from alley wayInterior Floor 1First two rooms total of 408ft^2Carpets removedHardwood finishedWalls/Ceiling Painted w/ 8ft ceilingsReplace Windows - 3(2.5'x5'), 1(4.75'x5')Small Foyer 39ft^2Flooring (tile?)

Read your lien laws, maybe it shortens the window to file a lien.  

Its ok to have a 10k window, such as, the house having an ARV of 260to 270ish, but you do not want to have a 50k window.

We have been in a window of about 2 years where flipping is a solid opportunity in some markets, but that might stall out in another 12-24 months depending on what the economy does.I know the above is not an "answer", but perhaps a means to ask the questions that will lead you towards what is best in your situation.

So I walked onto the property and looked through windows and decided it was worth making an offer in it.

I also had budgeted new windows for the entire house. 

I'm in each of my units once a month at minimum and they know when they sign a lease with me that I know what tenant-caused damage looks like, and they'll be responsible for the repair bill when they break something ... window, door, toilet, faucet, switch plate, whatever.