you can easily cut it to usable sizes, use it for totes or it would work very well for your wall hanging. do not spray it with anything, you will really make a mess!
lots of people press large pieces of fabric...and battings, you have to do it in sections. i usually use the floor, i spread the batting out, smooth it nice and square, then put the top on top of it making sure everything is nice and smooth...press until i have the complete top pressed to the batting, let it cool, then turn it over, smooth it out again place the backing on, and press. i always pin or stitch baste around the edges to really hold it when quilting but not everyone finds it necessary. you can just baste and quilt and ignore it's fusability but spray basting will not work with it.
when i use my floor i make a large ironing board...i put down a couple layers of batting then a piece of muslin over it to work on. i do not press the sandwich right on the floor.