2. At certain level, some tanks gains dps to perform single target rotation when there are only 2 enemies around. It's probably not a huge gain but you'll be fine so long you swap targets. A DPS needs to do roughly 1000 - 2000 or more potency worth of damage to for every tank's 100 potency in order to steal enmity under tank stance. If a DPS manage to pull enmity off the tank, then somebody's gotta stop watching their netflix.

3. In spirit I agree. Not so much in practice however because you really never know how far can you go until you give it a try. Speaking from healer PoV here, if you keep babying healers---especially if they are the notorious Freecure/Medica II Mage/Benefic II Mages---they will never learn that they have all other existing tools to sustain their tank. A Cure I/Physick/Benefic I/Diagnosis Mage can keep you alive with those lv4 Spell through any wall pulls outside exceptions like Mt.Gulg first mega 5 pack pull so long you're tanking properly. Let that sink in.

Not to mention that healer's dps potential skyrockets in AoE encounter. Any healer worth of their salt WILL outdamages good amount of red DPSes in DF duties very easily. So, pull more > let them reap the benefit of their powerful AoE potential > let those obscure healing tools be used instead of collecting dusts > pulls dies faster.

4. Depends on which AoE you're up against. It's a good habit to build: see red carpet? Move out. But as a tank you have what people call "tank privilege". This is especially true as your tank & healer get synced closer to cap level thanks to their monstrous sustenance that they can provide. Did you remember some of your tools are sitting on the bench collecting dust? Perhaps you can think of 'that one' mechanic/AoE that you can just cheese. Go ahead and do that. Healer have $h!tton of those tools collecting dusts on the corner. They'll be happy to finally do something.

5. In general, yes. But in dungeon runs, it's generally preferred to just save your longer cooldowns for wall pulls because that's where most of the damage a tank will receive. Using the 90s ones early on a boss encounter because it'll come back up when that boss dies, but your short, auxiliary cooldowns are best used here to deal with tankbusters and whatnot. Those are enough. The amount of time I have to rub my temple when I see a PLD pop up Sentinel when the boss is at 5% HP just because the boss is casting tankbuster could probably make me a rich man if I get 3 dollar each time that happens. No, just save it for the upcoming pulls. We also regenerate 10% HP/MP every 3s outside combat, remember? It's fine if the tank finishes at sub 50% HP. Nothing's gonna kill them right off the bat.