Try clicking on the A/A icon (1st one on the left of the bar sitting on top of the box where you type your text, see if that gets rid of the "more than 10 characters" error message.
If you took the pictures with an iPhone or iPad, chances are they are too big MB wise to upload. Try mailing one that won't upload here to yourself, mine will ask me what size I want to send, tell it to send much smallere than the original size, then try to upload that copy of the picture.