The fun fact is I actually named WIPs in my scrapbook "Suicide Pinkie" (yeah, I know it's probably spelt wrong). But if serious, she's going to be fine, it's Applejack after all, who holds her tail (: And what about expression, I'm really not good at facial expressions, I wanted to show her really excited, with some pity mixed with joy.
The different ways I see it interpreted is what I said above, Pinkie litearaly helping you up, or Pinkie reaching out to someone (Maybe a brony or someone who isn't) and going to take them to equestria. What really helps emphise the point is the use of colors. With the sky and the ponies the colored and the wall not it really does give the impression of something better that they are offering to you. And since you have Pinkie jumping over just to get to you and AJ grabing her tail at the nick of time, It all adds up to a very amazing piece.
He-he, I could tell that it's actually why Applejack has that face, but this will be, of course, an excuse ^__^ You're right, I should draw Pinkie's tail a bit differently. I hope to draw once another picture and have a chance to make it correct (: