Regarding your circles, if you're making small (around grape sized) circles, use one of those teflon circle guides. Out of your fabric, cut a circle 1/4 to 1/2-inch larger than the finished piece and use a running stitch around the edge to make a yo-yo. Place the appropriate teflon circle on top, and draw the thread, gathering the yo-yo around the teflon circle. Iron well, allow to cool, and remove the teflon circle. Iron again. That's how I finally got perfect grapes, cherries, etc.
Good luck!
Ruthann