Hi Jenel,
I have used red thread for machine embroidery on off-white fabric and not had a problem.
Regarding the machine quilting, I would not give up yet, practice on an extra block. There are several books on just machine quilting. Alex Anderson has a very easy basic book to follow with tips and techniques.
Also, to enlarge a pattern from Queen to King, I would look at one of the quilting encyclopedia's and a book on borders which usually have a section resizing quilts.
Your quilt is beautiful, you are very talented! :D