That looks good what you have done! A fun little wall hanging for someone who wants a dash of colour.
Good new technique that you've created there!
As for the mitres, I usually overlay the pieces and either leave them squared, or turn in the mitre corners and let them flap in the breeze! I figure it's so tiny, that any extra hand stitching I do, would probably ruin the effect, more than letting them go au naturel!!!
Looking forward to seeing more of what your do in your use-up-the-orphan-spree!!
Another idea oprhan-user-upper ... check out this link
http://www.quiltingboard.com/picture...a-t219542.html