Willing to give you my time for free so if you need help with anything, ordering supplies, keeping track of costs, project management, etc., im willing to assist you.

These tanks, and direct vent gas furnaces/boilers, can be plumbed directly through the side of the building (foundation wall, sill plate, etc) provide the exhaust exists the required distance from an operable window, door, or other air intake.From an energy efficiency stand-point, direct vented fixtures are preferable as they are not taking their supply of combustion air from the conditioned space of the building (are you have already heated), causing colder, external air to be drawn into the building.Additionally, as Pat has pointed out, direct vented fixtures reduce the risk of natural gas/propane or CO being drawn back into the conditioned space of the home. 

On the other hand, if your supply valve/hose breaks underneath your sink, or your tub overflows, it's the units owner's responsibility.

There was severe smoke and water damage, and an existing sagging second floor from the weight of the water, but we knew that was able to be fixed.  

If you have multiple units on one system, and this being New England, I'm guessing it is an older building, you are most likely going to have to open up walls, and replace a lot of the supply and return lines so that they make home runs to individual boilers, etc that you will be installing.  

For example, the money used for the original purchase of the property is no more or less valuable than the money used to purchase supplies at a later date.

America after World War I stockpiled 70%+ of the worlds gold supply and his caused capital flows to pour into the U.S.

Operating agreement in place spelling out duties, financial responsibilities, and profit share as follows, Member 1 provide purchase money, pay holding costs and supply labor as able/ needed.Member 2 ( me) provide rehab money, manage contractors, make all decisions neccessary for completion.Short version.

My goal is to find a rental here (college town, built in supply), but it is very discouraging.

. $25k sounds like a lot, but when you install new roofs, HVAC systems, hot water tanks, ceramic tile, new supply lines to angle stop valves, vinyl plank flooring in high traffic areas, carpet in bedrooms, faucets, fixtures, electrical panel updates, etc. it really is not that much and important if you plan on a long term hold.