Maya rotate snap hotkey is j
j means rotate snap, because you know, in original english rotation by discrete amounts of 15 degrees was called “jotation”.
Anyway, double clicking the ROTATE TOOL gives you a box @ right, you can modify the size of the discrete step there.
If you notice, holding j “temporarily” clicks on the “discrete rotate” setting.
Maya vertex snap hotkey is v
If you hold v it will let you snap a vertex to another one while dragging.