1. For the Airbus its not a check that FCU and PFD/ND target values are the same, more to verify that the target has engaged. i.e When in NaV mode you can select a heading value, but if you dont pull to engage it, then NAV mode remains. The FCU only tells half the story. PFD and ND tell the full story!
2. Dont think there is any policy surrounding IRS order to align. I was originally training 1-2-3 sequence with the theory being when you have to switch one in-flight you are more likely to choose the correct one. “So is just a technique”.