I glue baste now, but the "rule of thumb" is basically the same....once a hexie is completely surrounded by other hexies, that one's paper can be removed....think of the center of the rosette after all petals are attached.....

And, yes, batt and back like any other pieced top........

...you can use the same template to cut out your paper pieces...use a different rotary and cut the paper at the 1/4" less than fab marking.........works in a pinch.......

I'm also addicted to hexies! I bought the fiskars x-large punch, makes 1 inch hexies, cut the paper from cheap posters at walmart. I don't re-use them because I do the sew through method. I don't remove them or the basting until they're completely surrounded like above posts states or if I'm going to applique them onto fabric, I just leave them and the basting in until I'm ready to press and sew them on. I cut my strips of fabric 2 and 5/8 just because I like a little more than 1/4 th, easier to hold down while stitching to me.