Silver Maple is perfect for lathe, chisel and file tool handles. Walnut is better saved for other things, like cutting boards, small boxes, trim inlays and that sort of stuff. Not that it wouldn't make good handles, just it's a little special for a utilitarian handle. I made my daughter a nice wedding goblet with the captured rings out of a "firewood" black walnut log. I like mixing maple, cherry and walnut in cutting boards. Gives them a nice traditional look.
When taping the ends of your blanks, remember it takes about a year per inch to dry wood, maybe less if cut in the fall, early winter. I have a box full of wood blanks of all sizes I keep. Some pieces are 40 years old. I would guess most anyone with a lathe has the same box:-). If you ever go to a woodworkers store like Rockler and price little turning blocks, you will instantly know why a nice looking hunk of firewood is worth saving.
Turning bowls, lamps, is most fun with green wood, the greener the better. Lot's of techniques posted on here for drying. I used to melt paraffin wax all over the rough turning and that worked. I'd try the paper bag thing I think. If you get checks, even big ones, you can mix epoxy and saw dust, or a variety of things and sometimes get result better than if they weren't there.