Around here, no question is a dumb question--we're all learning stuff all the time!! You are correct: when testing chlorine with the 10 ml sample, you multiply number of drops by 0.5, and if using the 25 ml sample, multiply by 0.2. That is your result.

I'm not sure what you mean by FC levels between 11 and 12.5--do you mean that you tested twice and got two different results? Either way, as long as the CC was zero, you've pretty much achieved conversion--congratulations!! Your pH and alk are fine where they are. So.....change the sand, test for your CYA after a few more days, keep your Cl at 2-4 until your CYA registers, and at that time adjust your Cl upward based on the CYA level, and.....ENJOY YOUR POOL!!!

Janet

Edit: Just to make things easier, when you draw a sample for testing, take your cup, invert it, put it into the water as far as you can reach, and then turn it right-side up. This will fill the cup with water from deeper levels in your pool than the surface. If you'll run your tests from this, then you shouldn't have any variations in the results.