Okay, I've checked on the developer's forum and this seems to be a general issue with iPads.
The two currently offered solutions is to use the mobile skin (which you've confirmed works okay) or to disable RTE editor.
But, will you try this for me please - using one of the regular skins, click on the smiley icon to expand them into the right side, then click on a smiley - any one, doesn't matter.
Does it appear in the post content box?
Okay, can you click/tap in the content area and can you now enter text?
Cheers,
Shaun