Is the roof causing any problems-ie is it leaking?

Leaks after install and blames it on the siding? 

Ideally you know the existing paint (color and sheen),  but if you do not the various paint vendors can create a match from a modest size paint sample.As for the profit with $200 to $400 per door, That profit should be after allocating for all expected expenses including tenant turn over costs, vacancy, maintenance/cap ep, PM (charge for PM even if self managing because it is work and you deserve compensation for doing the PM duties), PITI, and the various miscellaneous costs (such as portion of LLC cost, portion of umbrella policy, portion of office costs, unexpected costs (for example if a slab leak occurs, we pick up the excess water charge as it would not be right having the tenant pay this cost - these types of items are irregular but they do happen and should be accounted for), etc.). 

As long as the roof still serves its functional purpose, meaning there are no significant leaks, and isn't completely damaged, then more often than not you should be in the clear.

We will be closing this week and we will rehab: change roof, repair the leak in the windows, water heater, update bathroom and kitchen, and probably the floors (if we have enough budget).Thank you so much for your help in advance!

Meanwhile, both first floor units have a leak under the kitchen sink.

Quote from @John Leake: I do not have first hand experience but a few companies that come to mind are Foremost Insurance which I have used for non occupied property as well as USLI Insurance. 

If you have to do it every two weeks, there may be something else wrong with your pipes (like a leak in the P-trap).   

Good morning allI'm currently rehabbing a house in Pennsylvania for rental and everything could have gone wrong went wrong.Anyway, I'm having so much issues with the plumbing system from cracked cast iron radiators to leaking pipes that the company that I hired said it will be better for me just to replace the heating system with Mini split ductless system, 5 of them for a total of 25K, my business partner is concerned that it will not be a good idea since the basement which is unused and unfinished will have no heat and pipes in the basement can break from freezing temperature and eventually cause more damages.

Things will break and leak, you just have to be mentally prepared for it and be able to recognize what is an emergency and what is not and have people lined up that can help you with the process.