I'm also curious how much it costs to prepare the land and install plumbing, electricity, and concrete (driveway, walkways, patios).I'd love all the insights I can get from anyone that has experience doing this.

The assessment was for replacing all of the railings and walkways in the building - those replacement costs should have been built into the budget of a well-run HOA. 

You have to meet Commercial code, ADA units, fire sprinklers, elevators (maybe), walkways, exterior stairways, etc.

Make sure you have a plan to apply salt to icy walkways.

I'm also curious how much it costs to prepare the land and install plumbing, electricity, and concrete (driveway, walkways, patios).I'd love all the insights I can get from anyone that has experience doing this.

Completely renovate the kitchen, 2 small size bathrooms, floors all over, "freshen up the windows" (windows were pretty old but contractor said we might not need to change them), cut off tree branches on top of the roof, add a walkway in the front.

Since it's worth $1.3 million and she bought it for $550,000 and she owns it now with no mortgage, It sounds like she needs to calculate if she (or they when they get married) walk way with more proceeds from doing a 1031 exchange and the depreciation recapture vs. using the $500k exclusion for primary home owners)?

Because we did the majority of the work ourselves, the total rehab budget wound up being around $30,000 (which includes adding a deck, fencing in the huge back yard, fixing the driveway and adding a paver front walkway.)

Same things that you mentioned as well as no floors, 2nd floor walkway needs to be redone and so on.

How about snow plowing of driveways/walkways?