Unless there is a some urgency or distress , there may not be a bid variance for the seller in taking less for cash offer ( number 1) as the net effect of proceeds will be similar. 

I've got an architectural design picked out, a contractor selected, and I've got the family ready and willing to move into one of the units.

How do you feel about the effects of gentrifying neighborhoods?

The mantra of "the buyer's agent costs you nothing" is typically reiterated by realtors working as buyer's agents and it is a terrible misconstruction of how having a buyer's agent actually effects the deal.

I will just have to be much more selective in what I invest in and where exactly.

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Which is the most effective, straight-forward and safe one to go with (That you are most likely using as well)?

In order to do this effectively they are typically distressed properties or if you are fortunate an off market smoking deal.  

What's the best time/cost effective way of dealing with it?

Interested in hearing what experienced investors consider when selecting a property to invest in.