Along the way we have come along some unforeseen costs that will force us to eliminate some of the design work we had in place.

Should I force them to give me a lump sum? 

No matter how good a Realtor is, they cannot force the other party into terms. 

Lastly are there any potential hazards that could increase the impact of windstorm damage to the property?

You also need a 'reasonable' excuse to move out, either family growing, or getting a job at a different location, forcing you to move. 

If appraiser calls out repairs, and you choose not to fix them, the bank will be forced to fix them if they want to sell VA in the next 6 months.

A busy road can have more of an impact than you might think.  

Now, maybe the planning commissions haven gotten smart since the crash of '08 and stopped approving so much building but that housing glut had a sincere impact on the housing crash back then.  

I reached out to them directly because I was trying to find housing for a group with special needs that was being forced to move because their rental home was being sold. 

She will be a toxic tenant if she is "forced" to stay in the lease.