  Helical edge states in quantum spin Hall (QSH) materials are central building
blocks of topological matter design and engineering. Despite their principal
topological protection against elastic backscattering, the level of operational
stability depends on manifold parameters such as the band gap of the given
semiconductor system in the 'inverted' regime, temperature, disorder, and
crystal orientation. We theoretically investigate electronic and transport
properties of QSH edge states in large gap 1-T' WTe$_{2}$ monolayers. We
explore the impact of edge termination, disorder, temperature, and interactions
on experimentally addressable edge state observables, such as local density of
states and conductance. We show that conductance quantization can remain
surprisingly robust even for heavily disordered samples because of an
anomalously small edge state decay length and additional protection related to
the large direct gap allowed by glide symmetry. From the simulation of
temperature-dependent resistance, we find that moderate disorder enhances the
stability of conductance by localizing bulk states. We evaluate the edge state
velocity and Luttinger liquid parameter as functions of the chemical potential,
finding prospects for physics beyond linear helical Luttinger liquids in
samples with ultra-clean and well-defined edges.
