One of my references had a handwriting that was barely legible at all, and to decipher the e-mail address HO must have had a cryptographer. Anyway, application went through smoothly, nobody cared. So far, I have never heard of any case when HO trashed an application because of the references scribbling. Relax!
Photo-wise,
guide AN specifies that you should "staple or clip" a photo, while
form AN just generally mentions that you have to "fix" a photo to the form. Again, I don't think it makes any difference at all - staple, clip, glue, ... whatever floats your boat, as long as a suitable photo is attached.