Dishwashers can be either hardwired, or cord-and-plug connected. Check the owners manual of the unit you have, but in most cases the decision is left to the installer.
From a random Maytag Dishwasher Installation Guide (PDF)
In newer homes you'll commonly find a 125V NEMA 5-15R receptacle supplied by a 20 ampere circuit, used to supply a dishwasher and disposer. In this case, the receptacle is typically installed in the cabinet under the sink. If you don't have a receptacle under the sink, it's not likely that the dishwasher is cord-and-plug attached.
The National Electrical Code, specifies that all outlets must be accessible. Because of this, a receptacle installed in a location that requires the removal of the dishwasher is not code compliant. i.e. If you can't find where the dishwasher is plugged in, it's likely hardwired.
Checking the wiring for the disposal, might give you some clues as to how things are wired.
You might also find This answer useful, when trying to figure out what you can connect to the circuit.
Code that allows Garburators and dishwashers to be cord-and-plug-connected
National Electrical Code 2014
Article 422 Appliances
II. Installation
422.16 Flexible Cords.
(B) Specific Appliances.
(1) Electrically Operated Kitchen Waste Disposers. Electrically operated kitchen waste disposers shall be permitted to be cord-and-plug-connected with a flexible cord identified as suitable for the purpose in the installation instructions of the appliance manufacturer, where all of the following conditions are met:
(1) The flexible cord shall be terminated with a groundingtype attachment plug.
(2) The length of the cord shall not be less than 450 mm (18 in.) and not over 900 mm (36 in.).
(3) Receptacles shall be located to avoid physical damage to the flexible cord.
(4) The receptacle shall be accessible.
(2) Built-in Dishwashers and Trash Compactors. Built-in dishwashers and trash compactors shall be permitted to be cord-and-plug-connected with a flexible cord identified as suitable for the purpose in the installation instructions of the appliance manufacturer where all of the following conditions are met:
(1) The flexible cord shall be terminated with a grounding type attachment plug.
(2) The length of the cord shall be 0.9 m to 1.2 m (3 ft to 4 ft) measured from the face of the attachment plug to the plane of the rear of the appliance.
(3) Receptacles shall be located to avoid physical damage to the flexible cord.
(4) The receptacle shall be located in the space occupied by the appliance or adjacent thereto.
(5) The receptacle shall be accessible.
Can I merge two ceiling light fixtures into one with two wall
switches?
To answer your first question, yes. Almost all light fixtures have a white and black wire for each individual socket. Simply send one to each switch.
Do I just make one of the wall switches a three-way?
Well you will need a "traveler" (extra wire) between the switches for a 3-way. There are a couple of different ways to wire a 3-way here but if your walls are closed and you don't want to open them then the answer is, no.
Best Answer
2 KVA per home (2000 watts) is what the power plant uses when they're bragging about how many homes their plant powers. They're talking average use.
What really happens is you have high extremes of power use. The family chef has the oven, 3 burners, a George Foreman and the toaster all working at once (and a crockpot for sauces), the water heater is constantly recovering from dishwashing, and all that heat in the house has forced the AC to 100% duty cycle. Once dinner is called, all those loads will poof disappear.
You have to size the system for peak use.
OK, so you think "fudge factor", but this is like a fudge-factor of fifty. No, you gotta sharp-pencil engineer this out. Or just put in really good service and not worry about it.
Maybe you're thinking about it upside down
You're asking "how little service can I provision". How about asking "how much can I get for sane cost".
Adding electric capacity is dirt cheap. Spend an extra $500/unit on the parts to do it right, and it'll last 40 years, and that's chump change for something that'll last 40 years. It's a loser's game to pinch pennies on service, only be forced to upgrade later. Especially if, once permitted and occupied, the city requires a licensed electrician to do the work. As a homeowner subdividing yourself, you can DIY that stuff for pennies on the dollar.
Ample service also saves money on appliances. Electric on-demand water heaters are half the price of gas, and don't require a vent. My landlord put in a $1200 gas one because he had no choice. Ditto dryers - tenant-grade electric washer-dryers are commodity.
Better service also means better tenants. Tenants who are constantly fighting tripped circuit breakers are going to believe your electric is hokey and you're a slumlord, and are not going to stay. At extremes, "Can a circuit be added for my electric car" is a wonderful question because it means a wealthy tenant who'll be staying awhile. You want to giggle with glee going "Oh yeah! We can do that!"
If the conversation with the electric company goes something like "Well we could bring out 400A service, but it'll cost ya (more than you wanna pay rght now)", then make everything else ready for it, so they can just cut it in without additional work.
If the game is make max money as a landlord, squinting at price tags at Home Depot is barking up the wrong tree.
Commons service
Keep in mind Code will certainly require you to have a separate meter for commons-area loads. This could be impressive, like an electric dryer or shared on-demand water heat; or it could be trivial, like five LED lights.
I have to say, in the latter case, I would consider going off-grid solar for a few LED premises lights. It's far cheaper than the cost of a monthly meter fee.