Shut off the power to the light circuit. Remove the old light switch if there is one. Remove the old lamp holder base. Make a diagram and note how the wires were attached, what colour screws to what colour wire. At the light switch wire nut the two wires that came off of the switch together. The switch plate cover will have to be replaced with a blank cover plate to cover the old switch box. Install the new pull chain lamp holder using the notes and diagram that you made. Some of the lamp holders that have a switch in them will not have terminal screws. The wire to the switch will be the "hot" wire. The other wire from the old lamp holder will be the neutral which should be a white wire. Insert the bulb and turn the power back on. Now the pull chain will control the light rather that the wall switch.
No, the fixtures do not have anything is common other that emitting light. If you are talking about removing the fluorescent fixture and installing a new fixture that can take a LED lamp then the answer is yes.
30 inches
Yes. The Home Depot has a kit for about $10 that converts a recessed can to accept a standard fixture. Weight limit is about 10 pounds.
You should be able to as long as you can mount the fixture. Then just remove the plug and hard wire the wires right into the circuit.
A fixture is what the light bulb goes into.
there are no rules for this, just personal opinion commonly installed with about 48" in between table top and bottom of fixture
The standard height from the top of your table to the bottom of the light fixture above should be between 30"-36". Also the size of the fixture should be a little bit greater than 50% the width of the table itself.
If the base plate can be removed than a chain ring can be installed with another chain ring installed on the base plate. Add the chain and wires and you have a pendant lamp.
Standard rule, top to the fixture same height as top to the door.
Yes. For more information open discussion question page with more details as to what you want to do.
Take the nut off at the bottom of the light fixture by unscrewing it.
If you are talking about a fluorescent fixture then yes it can be done. As for the cost factor it wouldn't be worth it. To buy a new replacement 120 volt ballast separately would be equal to or higher that getting a whole new 120 volt fixture. Do a price comparison before going ahead and making a change to the 277 volt fixture.