jelly rolls are 2 1/2" strips X width of fabric- so generally about 42" long. there are many patterns out now days for using the pre-cuts- you can use them anywhere a 2 1/2" strip is needed- or you can trim them down to 2" or 1 1/2" strips (honey buns) not sure what you mean by 'edging' your quilt- adding borders? generally you don't want to border to over power the blocks- and often the border measurement is an amount that will 'go into' the size of a block (like a 12" block can 'handle' a 6", 4", 3" or 2" border) a 9" block generally goes well with 4 1/2" or 3" borders- but there are always exceptions. if by 'edging' you meant your binding- some people cut their binding strips 2 1/2" wide- others prefer a narrower binding- strips are cut, joined, pressed (wrong sides together) then the raw edges are placed even with the outer edge of the quilt- stitched to the front of the quilt (after the quilt has been quilted & trimmed/squared up) then folded over to the back & hand stitched down. there are lots of tutorials when you have your quilt all quilted & ready for the binding- don't worry about it until it's time.
