By the way, read "The Photoshop Method" (second section) on this page. It's written to be used with my web watermarking action, but applies generally in your case too.
Nothing at all. Relax.
What about if you check the Image Size immediately after cropping, before saving or closing or reopening?
By the way, I strongly suggest clicking on the little cog in the Options Bar, and choosing "Use Classic Mode".
This is difficult for me to address, because I can't really tell which part of the process you don't understand.
Do you know how to add a drop shadow via the "Fx" button in the layers panel?
I don't even think cloning will work, to be honest. You'd need to do a lip swap from another photo, if possible.
Or embark on some very painstaking lip creation.
Or simply accept that the bubbles are freakin' gorgeous, and leave them.
You've got the layer thumbnail selected, rather than the mask thumbnail. Click on the mask thumbnail in the Layers Panel, so that it has the little border around it.
First, a Levels layer and move the black slider on the Red channel to 20, and the black slider on the Green channel to 5. Mask it to the circle.
Then this to tidy it up.
When you crop, do you see the photo changing size on screen? It should remain exactly the same size (apart from the removal of the cropped edges, of course).