My quilts were much smaller than yours but they turned out great. I don't think I'll ever use pins again. I followed the instructions that I found right here on the board - not the pictures so much as the written instructions.
http://www.quiltingboard.com/tutoria...e-t208057.html
Not only is 505 a lot more expensive, I just can't imagine breathing all that stuff in. I already have COPD and Asthma.
I did not heat press my glue efforts as I also use poly batting. Instead, I did the back, let it dry overnight and then did the front the next day. It held really well but I don't think it would have been difficult to INTENTIONALLY pull the fabric away from the batting.