1. You're alkalinity causes the pH to rise over time. This page explains what's going on:
http://www.poolsolutions.com/gd/lowe...p-by-step.html

2. I'd recommend starting with a 1/8 - 1/4 gallon dose -- don't measure, guess. That may be too much, but with your TA as high as it is, it will just climb back up. (The good thing about muriatic is that it's really, really unpleasant long before it's really dangerous -- but still, if you don't try to pour and measure, you won't get a snoot-ful)

3. Do continue with 1/4 bottle of bleach each evening. If your pool's FC gets too high, skip the next dose.