For PvP, you want endurance augments as the amount of damage that gets mitigated in PvP is less and far more unpredictable to budget for mitigation completely.
There's no set way to augment your tank. You augment what you need to reach your desired stat budget for mitigation. I would recommend not augmenting for shield, but for defense and absorb. For your mitigation values see this thread.
The changes to Shadows/Assassins in 2.5 didn't really change your rotation much or how you played the class. The new mechanics in fact make it more mobile than ever before. I'm also confused as to how the changes effected lore or RP. It actually makes more sense that your flying debris absorbs damage prior to it coming to you rather than throwing debris at someone healing you.
Can you elaborate on how the 2.5 changes effect what you listed?
<Aisthesis> raided the Hoth Imperial Base today. Loads of fun!
Thanks <Guerilla>, <Nova Imperium>, and whoever else showed up to defend the base on impside.
http://i.imgur.com/40RXDp4.jpg