Dragoons: A Rotation Reborn

[Hivernica]

As someone who mains bard and decided a few days ago to FINALLY get Blood for Blood (my lancer was lvl22, just enough to get Invigorate), I used to hate lancer since I'm a sworn ranged classes lover. But while doing the class quests and more dungeons, I came to appreciate it. I am now a lvl31 dragoon and this thread really helped me. Even though I'm still low level I memorized the entire lvl50 rotation this morning (bored at school...) and really appreciated the help this thread provides. Right now it has 263 pages, and I'm not sure how I can find answers to my questions, so I'll just ask them here.

When switching targets, do I start my rotation over or just continue as I was doing?
At lvl50 while killing trash mobs that won't live long enough to justify the use of 3 DoTs, what should my rotation look like?
Right now at lvl31 Impulse Drive doesnt boost any other skill and doesnt quite fit in my untraited Heavy Thrust's buff duration. Should I still use it or wait until I get Disembowel?