Redwork really just means the colour thread you use to stitch the picture - with and with this type of embroidery, you usually just stitch the outline and highlights of the inside. It's both a quilting and an embroidey technique (penny squares - redwork squares - were stitched and then made into quilts).
The term redwork comes from the red ink used to print the squares - and the ink was so thick that you had to use red thread so that the printing wasn't so obvious.
I like to use dressmakers carbon to transfer designs to fabric.
You may want to check out the article on it - which can be found here:
"Transferring Embroidery Designs to Fabric" article It's not actually necessary to turn it into an iron on transfer to get it onto the fabric.
Hope this helps.