The main advice I would give to tanking is to be flexible. Because I am not yet in a guild, I mainly run with PUGs (and a few preferred flashpoints/heroic partners when they are available) and it implies that the group structure is always different. As such, being flexible in which skills you employ at which time is key to success. Flexibility is a compromise between using or not using your abilities with cooldowns. Instead of having a rotation, I prefer to focus on different stages of combat based on how the ennemies will react to the group's actions. For instance, instead of nuking down an enemy by burning my rage points ASAP when I know the targets tend to lose interest in me if I'm not pounding them, I'll use one enemy as a "rage builder", using Sunder-Assault-Assault-Sunder until I have enough rage point to unleash hell on a stray enemy that doesn't give me the attention I deserve. I would also suggest to use the long CDs abilities as early as possible (Saber Ward, Ravage asap after a couple stacks of armor reduction, Enrage) in order to have them activable a second time in the encouner if needed, or to have them ready without too much downtime for the next fight. Last advice I would give is the smart use of the "Guard" ability, which transfers part of the damage and threat from your guided target to you. For the first encounter, guarding the healer is usually the most sensible choice, but if he doesn't take aggro, guarding your off-tank or high output DPS is probably for the best. Finally, don't stress. A tank must remain cool headed and relish every bit of doom it brings to the enemy to remain flexible to control the mobs. I would suggest to learn each skill individually, and figure out how you can best use it in combat, without focusing on predetermined rotations because it will soften your mind, while you need to be attentive. In terms of specs, I don't beleive in flavor of the month builds. Go with the skill that support your playstyle and give you an edge in combat.

I would totally do that. For example, on the last Athiss run, I rolled for a chest piece for my Sith Warrior which I did not want to wear because of the looks and its color pattern, but I was interested in the mods for my custom chest piece which appearance suits me as of now. There was no other Sith Warrior in the run, but I would totally roll for it if there was. I expect others to roll for it as well.