capacitive or resistive leakage could be the cause of the dim glow. since you have parallel wires in the cable between the switches, the capacitance can be as high as 100pf/ft. it only takes 3V for a white LED to conduct at very low currents. assuming 12ft between the switches, that's 1200pf with a capacitive reactance of 2Meg. that gives a forward current of 60uA, probably just enough to produce a tiny bit of light. there could also be a tiny bit of resistive leakage in the switches.
it's called a 3-way switch most likely because it uses two SPDT switches that each have 3 connections rather than SPST switches which only have 2. more technically it could be called a 4-way switch, because it has 4 states and is similar to an XOR gate in function. so, calling it a 2-way switch is correct because it can be operated from 2 different locations. it can (kinda-sorta) be called a 3-way switch because it uses 3 terminal switches (or the alternative, that the cable between the switches has 3 hot wires). and it can be called a 4-way switch because it has 4 states.
we americans are fond of making up all kinds of "memory tricks" to remember things, and since the switches themselves have 3 terminals, it would be easy to remember what switches were needed for the job by calling them "3-way". it's inaccurate, and a bit lazy, but it gets the right parts the first time.