I would tell people today that if you buy a primary residence expect to stay in that home for atleast five years, especially with a FHA loan which has lower down payment as the current forecasts for home appreciation or very low which with closing costs on the buy and sell, it will take several years to have equity in the property and enough to be able to sell, so that is something also to consider.

Looking my insurance policy it mentions that I can opt for settlement under Actual Cash Value vs Replacement Cost. 

I don't have a garage or any parking so that could hurt the monthly rental appeal. 

Is there any good rules of thumb to estimating the cost of a boiler?

So, I would expect to lose 3 months rent maybe more.

After 2 months going back and forth with them, they finally ended up paying 50% of the $9000 bill.

WHAT IS A COST SEGREGATION STUDY?

I'm looking at monthly cost to seller vs. anticipated rental income, purchase price relevant to the ARV of the area and interest rate, balloon, etc.

The reason not to upgrade, is that you won't get that much more income for the cost of the upgrades.  

These methods include: Detailed Engineering Cost ApproachDetailed Engineering Cost Estimate ApproachSurvey or Letter ApproachResidual Estimation ApproachSampling or Modeling ApproachExperience or “Rule of Thumb” ApproachIt’s important to understand the differences between the approaches including which one best fits your property and the reliability of each approach.DETAILED ENGINEERING COST APPROACHThis approach compiles the costs from construction and accounting reports to build a report.