Well,addin that in my head,I come up with .492. That is really thick for 63# even with .006 taper unless your limbs are very narrow. So, my wild guesses(not gospel by any means)
1- around 10#
2- glass is stiffer and heavier than wood,so yes
3-between 5 and 10 #s
.006 is a lot of taper,does the current bow stack towards the end of the draw?
Binghams chart shows a strait longbow at 68" having .427 butt thickness with .002 taper for 65#.
Please don't take this as criticizm,just thinkin out loud! LOL