my rentals are in Hollywood, the best was some years ago when I first started, got called to a very nice ladies apartment for some general maintenance, I had seen her at the building in passing and made small talk previously....but, what I did not know until that very moment when I walked into her apartment, was that she worked from home, as a dominatrix.....she had a 4x4 cage in the middle of the living room, chains from the ceiling, leather covered saw horse, and a rather large opened armoire filled with every size and type of wips and various other adult devices.

Yes I guess it's a 'special' device that is designed to prevent any sewerage back flowing into the basements etc.

I know something about this from personal experience.There are alarm clocks with vibrating devices.

If the property is in a flood zone, but the house first floor and any mechanical devices are above the right elevation, you can significantly lower your flood insurance to a rate that could be very reasonable. 

Mostly this would just be a problem if all 4 tried to take a shower at once.As far as billing, you could put the gas on a separate meter (of the owner meter, if there is one), then put separate metering devices on each HW lead to the 4 units.

He says it would improve home resale value and we could use 3-prong outlets (that actually serve a purpose) so things like PC's and other devices that require that plug could have grounding.Has anyone done this or have any insights? 

Taking away ground will make a device more sensitive to damage from ESD (shocks, power surges, lightening).

Do you have things in your possession worth money that you don’t need (think fancy new devices when older ones would work)?

It is a low power way for devices to communicate.

Do you have listening devices/cameras in your listings?