Determine the line phase and line to line voltage
"Is the equipment rating in line-neutral volts or line-line volts?"

Nominal voltages for three-phase equipment are always specified as line-to-line voltage, regardless of if the equipment is intended for connection in delta or wye.

In your case, the transformer is 13,800V line-to-line LV, and 120,000V line-to-line HV.

Occasionally, both the line-to-line and the line-to-neutral voltage are specified; as in a three-core cable labelled "11/6.6kV", with 11kV worth of insulation between phases, and 6.6kV of insulation between each phase and ground.

What is the turns ratio across a delta-wye transformer?

In a three-phase Dy transformer with voltage ratio 1:1, the delta winding will have \$ \sqrt{3} \$ more turns than the wye winding.