Pld is quite simple in endgame. You have 3 combos and two stances. Try to keep Goring Blade up, use Royal Authority whenever possible and use RoH when you need the enmity. If you and your healers can manage Sword Oath, then that's better DPS, but this tricky because if you are in a raid group with really good dps, you will lose hate in SwO without RoH.

As a tank, it is common to be the raid leader for call outs and things of that nature, but not at all required. Just depends on the group.

Honestly, it's just a matter of learning the fights so you know when to use your cooldowns. There's not really much difference in endgame for tanks. The only thing real tank mechanic that's not used in leveling is tank swaps. Everything else is pretty much the same. Do as much DPS as you can while rotating your defensive CDs for big damage hits.