We would have readily said yes to replacing it (it was on our short list of things that we wanted to fix before we found out about the move) but the fact that it was replaced without asking first was not cool. 

Meanwhile, because hot air is full of moisture, all that water hanging out in your attic is causing condensation to build up.

I don't know what are you are looking at but around here you can estimate about $60-$80 per foot for public sewer and $80-$100 for public water. 

Let me know if I can help in any way, it's really cool that you are helping your brother get started!

Wood is like a sponge and if you dip a sponge in a bucket it can only soak up so much water, same sort of situation.

They may have abandoned the electrical before installing the water. 

The most common expensive things are water damage from washing machine hose breaks and leaks, facets that fail, clogged toilets flooding, sinks backing up and things like that.

The more you places you get through the more you will understand things like termites, plumbing, foundation issues, water in the basement, asbestos ... and the list goes on.

How old is the furnace, water heater and roof?

@Jake Fugman I didn't know that, very cool!