Vernelle

Maybe put some fiber paper underneath to stop the bending.

There are some older books that describe how to build your own kiln.  I think they are the Boyce Lungstrom books.  Or check the archives at http://www.warmglass.com.

I have done a flip and fire and gotten rid of smaller bubbles.   Doesn’t always work but worth a try.
 
I flip and fire

if the bubbles go away ..I fire again on the design side to get the glossy look.

Are the nozzles stopped up?

Have you checked Diamond Tech. site?  They are the ones who have been producing it for the past few years.
 
http://www.diamondtechcrafts.com

I did accent tiles for my kitchen backsplash.  I went and got the size of the plain tile from Lowes that I wanted to use and that is the size tile I made.
Mine are two layers thick.  There may be a little difference in thickness but the grout lines hide that.  They stay square as long as you don’t over fire them.

Looks like they may be using the decals that you can put in a printer and print whatever you want.

I put small pieces of scrap glass on each corner to keep the edges from curling if the paper is cut too big.