100 Base T just refers to a networking standard that allows for data transmission upto 100Mbps.
Full duplex means data can travel in both directions down the pipe simeltaneously, where as half duplex would mean data can travel down the pipe, but only one direction at a time. Simplex only transmints in one direction.
The TX refers to the cabling it just means two pairs of twisted pair wires. FX i believe is fibre optic and there is a T4, which i think is four pairs. I'm not entirely sure why you are differentiating between Base-T and Base-Tx though
just set it to autosence