In general, which is the phase relationship between the primary and secondary voltages of an ideal transformer? Does it depends on the dot convention?
which is the phase relationship between the primary and secondary voltages
The dot convention tells you which terminals will have secondary and primary voltages in phase: -
Above picture from here. Consider also this picture of two identical windings wound the same way: -
For any secondary load current, the primary load current will be 180 degrees out of phase at the dotted terminals. Consider this picture for the current: -