Hope this adds value:
I don't think the seepage is a problem. Old buildings such as that bound to have vertical cracks in the basement and those are easy fix if that this the problem. As far as tuckpointing goes, ask your agent or someone that knows tuck pointing if that something that you need to be concern about.
Windows are tricky - is it really bad that you need to change it? if its not that bad then just leave it.
Boiler can last for a long time as long as you maintain it.
You have to account that if you unzone the heating unit that you are buying 4 separate units not to mention the cost to do it and will increase your capex. The easiest way is to add the heat cost to the rent.
I understand buying your first deal is scary and there's a lot of unknown but hopefully you have a good agent that knows what they're doing and trust them. It doesn't matter if the building is a new rehab. The inspector will still find something that you might have a concern about.