ssnare, I have done a bunch of X-stitch and stabilizer yes you have to use on the back if you are going to use it as a block. You would have to hand wash your quilt, the aida cloth will not stand up to a machine wash and make sure your threads are well secured. The wall hangings that I have done have to be hand washed and then blocked out to dry in order to keep their shape. Don't think you would be happy at all.
On another note you say your only keeping the original "5" group, how about the second set of 5, the swap was closed then so we stay the same also right? Then you opened it and are those the ones that will be grouped in 5's or are you dividing up that second set also??