I have a torchier floor lamp that has a maximum bulb wattage of 100watts. Is this maximum wattage determined by the socket? Can I simply change out the socket and replace it with another socket that can handle more wattage, or even a three-way bulb? I am not sure how much of the "maximum" is due to wires vs socket. Please respond in laymen terms. I have done nothing more in my life than change a light bulb. :) Thank you!

It could even be the shade, Exceeding wattage will make Manufacturer not liable should something happen. It may or may not be dangerous, could be their generic warning.
Maybe additional lighting.

You can get more light (Lumens) by using Compact Fluorescent Bulbs.

Sockets do play a role. Those made of bakeilite will have lower temperature rating than ceramic. Surrounding material type also play a role. Then there is the effect of the surrounding material o dissipate the heat.