Flannel is a loosely woven fabric that will shrink quite a bit when washed and dried, and many folks recommend two washing/drying sessions before using them. Some flannels are more likely to bleed when washed, so make sure you only wash like colors at one time. If I'm going to be making blocks with flannel, I buy an iron on stableizer (did I spell that right?) and apply it to the back of the flannel before cutting. Seems to work better for me.
I like to use flannel for backings because they make the quilt feel softer.
Good luck with your gift!