It is fair to express your disappointment that they exceeded the cost target you gave them. 

Of course "hoping" rates will come down is not a sound strategy so finding a way to assume a loan that already took advantage of low rates is a great option.If you were starting over and targeted a large SFH, would you try to maintain the property in a way that would still attract regular homebuyers (not investors) if you needed to sell?

I'd target areas near colleges or transit hubs for affordable properties, and I’d look into financing options like FHA loans or creative financing to make the most of my capital.

Acquisition Target: $730K-$780K; ARV: $900K; Repairs: $120K.

Those properties that are obviously vacant - as well as those you advertise for 'immediate occupancy' are well-known targets of squatters. 

BRRRR is much easier doing commercials.

No guaranteed way to stop a determined, experienced thief:(Only deterrents that push them to easier jobs.The roof may be a good idea - until they figure out the just need a ladder to get up there and a rope to lower it down. 

First thing I recommend is to figure out your target market.

Real estate agents, property managers, and contractors who specialize in your target market can save you time and money in the long run.

If you used a loan to rehab your property and find yourself in a difficult position, doing a straight refi (just paying off the old mortgage) will be easier than trying to pay off the original loan and take additional cash out.