To answer your question, yes... Im afraid you've got one squirmy monkey on your hands but nothing that sounds scary or terrifying behaviour. Just a normal kiddo that is loud to go to sleep and wake up. A sample of toddlers taken out of a plane is just not enough, remember that spirited kiddos are a small percentage of the total population (about 10-15%) so normal yes, common, well maybe not that much (and it always seems to be a gang of angel babies when you're dealing with your spirited wee one LOL).
So to get started with Gradual Withdrawal, I'd start cold turkey in her room. IF tears are to be expected you might want them to work for the right purpose
. As long as you're next to her, she should be comforted by your presence and since you've been traveling for long times and periods, she shouldn't be too bothered about sleeping in a different room other than yours.
Then as for her loud "soothing", I wouldn't worry a bit as long as she doesn't need you through the process. She can whine, fuss, chew and do whatever she wants and needs in order to relax and soothe and spirited little ones seem to need some steaming off before unplugging. You mentioned she cried, but was it like a waaaa waaa cry? even if she's loud, i bet her cries are different than when she really needs you (say she's hurt or in pain or scared). The mantra cry, that cry some babies/toddlers use in order to go to sleep is more monotone and different than an actual cry. IF she's doing that mantra cry and is not upset or disturbed, just let her be, and don't interfere with that. It is totally normal and we're all entitled to do what suits us best (some people read, some other watch tv and some other do a craft... she likes to chew her hand and shout a bit... it doesn't sound weird or strange to me at all).
Now, if she needs you through the soothing process then we might have to think of a plan to help her wind down without taking so long and without much intervention from your side.
I hope you find some of this helpful and please keep us posted through your Sleep Training Process... we'll be here to support you and come up with some tips to make it more bearable. It shouldn't take you long if you're consistant. Good luck!