If there is opportunity to improve on both then many people will pay for that potential.

Pay down the mortgage and improve cash flow that way.Happy to introduce you to some lenders if you need them.

Assuming the improvements resulted in $1 of value per each $1 spent, you each now have a basis of $110,000. 

It is ideal (and will really improve your ability to successfully engage contractors) if you can float the construction draws3.

Typically if they are doing okay the business will hold off on major improvements and wait to move to somewhere else better.

A 0% rate can help get the monthly payment down which in turn can help improve cash flow. 

That would leave little to no room to make any improvements or save for cap ex.

I just got a triplex under contract in Tacoma, Washington, and during my VA loan process I learned that I can get up to $6k in energy-efficient improvements attached to my mortgage.

I would want mine first in this type of deal, and maybe just agree that my rehab fee is $300k for a list of improvements. 

In the latter case you maybe need some training in exam taking in general where you would learn some techniques to improve your test results.When I was teaching some classes I had some student that were very knowledgeable but were always scoring very badly in tests due to poor test taking training and stress.