I wish I could help you out. I teach T5 to people all the time.

She does her first death sentence just after plummet and healing can get very hectic if the OT had a messy pull. Your scholar should be healing you ONLY at this point and ignoring the drama happening with the scourges. They should have adlo up for every DS. Most scholars new to this fight don't know this and try to help the raid out a bit and will lose the tank.

After the first DS you can start to time them. DS will be cast after every 3rd plummet. You have time to pop CD during the cast but this way you can look like a pro and have your CD up already.

As far as getting specific drops, don't worry about it until you've downed her. The helm is great but you don't need the acc and the high Allagan drops in T6.