The rule of thumb is that the stabilizer should be 100% cotton, just like the fabric, it is adhering to.
The process is to turn your T-shirt design side down and put the stabilizer bumpy side down on top, then press with your iron until the stabilizer has fused to the back of the T-shirt.
A good amount of stabilizer (interfacing) for a T-shirt quilt is 10 yards. That sounds like a lot, I know!