OK folks! The last test results are in and I can tell you right now that this fabric and this paint are so unbelievably awesome it blows my mind!
I took my painted fabric with me to the pool last night where I proceeded to beat it senseless! Just kidding of course! I did rub it forcefully (while soaking wet) on the super coarse ledge and all over the pool floor. The paint didn't so much as fade! The fabric itself stood up super well too! And don't think I went easy on the fabric, I did my best to try to get paint off so I could see just how much abuse it could take in the pool.
I am super impressed with all of this so far and I am finally ready to take the next step with this process! Woo!