If you want to focus on Buy-and-Hold and your goal is to build cash flow......I suggest looking at markets where Turnkey operations are heating up.You want low purchase prices and relatively high rental income (another words, high rent to purchase price ratios).  

I like your ideas of turning up the heat a little (especially if the tenant is paying for the utilities) and installing a low flow shower head. 

However there's only 1 water heater and 1 furnace to heat the water and radiators (its an older rental).

Heated floors, USB outlets, special features in the kitchen?

Easy to get caught up in the heat of the bidding and overpay.  

If it's worth $790 for the piece of mind that you won't have to worry about shelling out thousands of dollars for a new A/C unit or heating system then you should do it.Best of luck!

The new construction buildings have higher ceilings, have more isolation in the walls, and all the common elements are brand new: brick work, roof, windows, heating system, etc. 

Same price as our multis, but new instead of a century old and a fraction the sinks, toilets, heating systems etc.  

Are they usually so much a heat loss during harsh winters that owners block them up or what?

Conforming bedroom in a basement -1) Proper ceiling height- varies around the country, usually between 6'-10" to more common 7', and this can get complicated if there are any soffited areas of the bedroom ceiling2) Closet- even a minimum size on this, usually 22" deep3) Proper electrical, proper heating requirements - must have a light and a switch located at the entrance, must be able to be heated4) Minimum square footage size of the room, usually 70 sq feet5) Egress - varies wildly in cost due to conditions, half below ground basement, fully below ground, walk out, set backs etc...Like Bill said - consult the local building dept, the codes for egress window wells are super strict, very detailed and can be confusing, they can get very picky, right down to if it needs a ladder the distance the ladder can stick out from the window well wall and then the clearance in front of the ladder to the window.Be very careful talking to anyone about egress windows with wells, this is one of the most screwed up things we continually hear about, and very expensive to fix if done incorrectly