Hi @Ross Bowman,One factor to consider with a beach house is proximity to the water and factoring in the flood insurance as well as the additional maintenance cost due to the corrosive nature of the salt water. 

That's likely where you're going to find some corrosion, and your plumber will suddenly tell you they have to saw out a significant section of the stack and replace that with Fernco couplings above and below the joint, which will require more demo than originally planned.Sadly, it's also likely where someone might to see a problem happening, realize that explaining the issue to you will take time and invite suspicion that he's cheating you, so in will go a single, much smaller Fernco coupling running to the 1 1/2 branch and a couple years from now you'll have to open the tiled wall up again.

One of the baskets has some minor corrosion on a few of the wires.I have seen a few DIY sites that says to use appliance epoxy spray paint.Anyone has experience with this?

I have heard of cases where a tank had had a small leak in the past, but then closed back up via corrosion, etc.

One area that I really support one is in the event the buyer/owner/landlord would not be able to cover a major system failure.In Arizona Water Heaters tend to have a life cycle of 7-10 years before the tank leaks due to the water and corrosion.

Seawater flooding, say, like Hurricane Sandy from Raritan Bay into Union Beach and Keyport is much more corrosive and catastrophic, than freshwater flooding that happens in a hard rain. 

Older BX is susceptible to corrosion in damp/humid areas (kitchens, bathrooms, basements, garages, etc.), so an extra look in those places is a good idea.2-pronged, ungrounded circuits for appliances which do not require a ground (lamps, radios, etc.) are perfectly fine.  

Avoid spraying the solution on metal or electrical , it is a corrosive .

Basically the corrosion restricts the flow of water overtime giving you very little water pressure.

This is likely caused by corrosion.