Re: airplane trip.. need advice.
I have flown a lot with my DS, but he's not quite as old/big as yours... which does change things. We always nurse on the take off and the landing (and when I am lucky, he stays latched and sleeps the whole flight). That would by my preferred way to do it, since it's the easiest for us. But, if that doesn't work for you, what about having her suck on something else? Does she take a pacifier? If she's sleeping, I would leave her alone - but be prepared to help if she wakes up because her ears bother her.
Other tips - make sure you bring more diapers than you think you'll need - just in case you have a delay. Also, I like to use zip lock bags to put the diapers in when there is not a garbage can handy.
It's also good to have some new-ish toys. That might keep her more entertained than something that she's used to always playing with.
When you go through security, make sure you are wearing easy shoes to slip off and on. Also, if you'll be travelling alone, it helps to have pants that slip off easy, in case you have to go to the bathroom when holding her!
Mommy to Alex (born 2/27/11) and Katie (born 3/31/14)