Libits it is a huge group of us that start quilting at a later age. As for stitching thru the blue, I would just continue with your red thread. Or choose a grey that would sort of blend in with the blue and red. After that has stabilized your quilt you probably need to do some sewing in the blocks. Your package the batting came In will say the recommend max distance between quilting. It can be anywhere between 2 to 10 inches