I totally agree about #2.  Not that I mind 
packing in priority mail boxes (if they're double 
layered or have the box and a layer of 
cardboard), I do it most of the time myself.. 
BUT it drives me crazy when people peel the 
strips off the adhesive.  I have fortunately 
never had a cel get damaged through it, but 
NUMEROUS sketches have taken massive damage from 
that annoying little strip no matter how careful 
I was.  Priority mail tape is free too, sticks 
well, and cuts easy.  
My advice (and what I do) is do not peel the 
strips off the glue on the PM boxes, and just 
tape the ends shut with priority mail tape.