If you go to top of the page and click on the Pool Math button, you can add your gallons near the top left (6000). Then under FC, use the left box to type in your starting FC and the right box for your target FC. Make sure and choose the correct strength (8.25%) and it will tell you exactly how much. So, if you punch in 3.6 on the left and 8.0 on the right box, it should tell you to add 40 oz. liquid chlorine or bleach.
To get to shock level for your SLAM, you need FC at 20 PPM because that corresponds with your CYA of 50. So from 3.6 to 20, you need about 148 oz.
I would stick to using the 10 mL sample for testing your FC. Just count each drop as .5 instead of .2 and you will save a lot of reagent chemicals. Otherwise, they will go quickly, especially if you have to SLAM and test several times a day.