About a month ago I had a contractor replace a roof that got damaged from a storm but when they had the shingles off another storm blew through overnight and blew the tarp off and a lot of water got in the house.

Your first is already risky enough since you lack experience, combine that with 100% funding and the risk is through the roof.

Multiple times projects took so long to get started or to get an appropriate bid, I ended up having to handle it myself (ie. roof replacement, unit turns, etc.) 

If the separating wall is a load bearing fire wall, it would have 2 sets of framing material on either side, essentially you have 2 completly independent houses joined by the roof, you can go in the attic and see if you see sheetrock going to the ridge of the roof. 

So you have a roof leak, the underlayment is rotted, they say they won't pay for it.

This helps me with pricing, and I try to keep those prices current so I know what to expect when putting on a new roof, or replacing windows.  

Got it.What we include in the process as well, is "how best to protect yourself from the "due on sale", what happens if the renter stops paying, what if the seller won't vacate, how to get a title report, why to not use a real estate agent, how does this affect my taxes, what makes for a good deal, what exit strategy to use, how do I hold title, what happens when the seller comes back later and demands to be taken off of the loan, how do I hold insurance, what happens when a roof or waterheater need to be repaired or replaced, and on and on.

For example, I’m doing three side by side duplexes and it’s costing me $135 psf, but I had to spend an extra $10k per foundation because of bad soil, and the smaller the property the higher the cost psfI’m working on a 28 unit with elevator, demo required, green roof, and it’ll cost me around the same psf as the duplexes.I’m doing three side by side triplexes which are full renovations, basement digout, all new facades, and that’s costing me about $106 psf for construction Non of these numbers include architecture, geotech, MEPS, environmental, utility plan, or finance costs

I redid the roof… it’s multicolored… used up shingles I had laying around… but still a new roof.Trying to decide if I should sell it.

Exterior didn’t need much – sharp new accent color for exterior doors, and other aesthetic enhancements, plus some upgrades on roof flashing and weatherproofing.We discovered that the ground level water intrusion was because a huge crack in a sloping sidewalk next to the building was funneling all the stormwater right over the sill, into the onsite-manager’s unit.