AWESOME IDEA-- I just learned from this. This is a great way to guarantee your pet has 100% accuracy for a run (assuming it doesn't die). You could use some DL caster accessories and the Vanya Chest Piece, for example (which have accuracy), as a set to summon your pet with, and then switch back to a hero's accessory set / Summoner's Doublet to get all the bonus damage for yourself without sacrificing your pet's accuracy.
EDIT:
For #1: If it's a single target boss I would say all you can really do is Ruin 1 + Ruin 2, + Fester whenever it's off CD (unless you're saving it for some reason), and make sure to constantly use Rouse whenever it's off CD. There isn't really much else you can do beyond that DPS-Wise, and it shouldn't be long before you need to refresh something (whether shadowflare or other dots), anyway.
For #2:
- You should always use Ruin 1 --> Ruin 2 unless you're about to move and trying to help burst something. (An example situation of this is if you get targeted with Fireball in Turn 5 and want to throw in some extra damage as you jump into the conflag guy. In that situation you'd throw the extra ruin 2 as you jump towards your teammate.)
- Same idea for Bio II and Bio, except that usually you will be going Bio II -> Miasma --> Bio as the bread and butter combo when you can stand and cast. (An example situation would be titan HM and getting targeted by the Granite Gaul before you get a chance to setup or re-setup your DoTs. It would be better in that situation to throw a quick Bio on him instead of Ruin II before you get encased in the rock.)
- Miasma II should only be used when all your other DoTs are already on the boss (and can get close to that boss safely). In an AOE situation, you want to spam Miasma II in the center of everything at the same time you spam Contagion, since usually you will want to Bane right after and the GCD's can be timed to work out fairly well (plus miasma II is hitting everything rather than a single target DoT).
- Tri-Disaster should be used when bane cannot hit all the enemies in an AoE situation, and should be used after the intial bane.
- IMO the basic AoE rotation that you got from Pandabearcat should be adjusted to using Shadowflare First, because it gives the tank an extra second to get hate on everything, will be hitting everything while you set your bread and butter up, and can save a swiftcast-shadowflare for a later point in DPSING the AoE group. It also allows you to hold that swiftcast should something come up (a party member or your pet dies from some reason) and you rather use it for resurrection / re-summoning.
- It's not a bad idea sometimes to use bane *before* contagion depending on what you're AoEing, and use contagion on a 2nd or 3rd monster before bane-ing again.
I do this at the beginning of Turn 5, for example, where I have that extra Aetherflow off CD at the start of the fight and the first add goes down fairly quickly-- it allows me to center more DPS on the #1 without worrying about it being focused down before contagion goes off or waiting longer before spreading my dots to the other two adds.. I usually target the #2 with contagion as I continue to DPS #1, and then re-apply my aetherflow stack + bane from the #2 to #3 so they both have the extended dots.