You'll get the hang of that kit after a few days.

You are right that using a 10ml water sample will save your indicator. It will give you a reading within 0.5ppm which is plenty accurate enough.

The CYA test is the most difficult to read. Do the test in natural light. Hold the tester waist high as you pour the solution into the test vial. Slowly add it until you cannot see the black dot. Don't test CYA too often. There is only enough solution for about 4 tests I think. If you think your CYA is about 42, then you should not use the trichlor pucks in a floater. Your level is good right where it is. Stick with bleach. It is cheap, readily available everywhere, won't add any more CYA and won't cloud your water. Cons -- bleach bottles to take to the recycling center. You can't go wrong using bleach.

Don't worry about the SI.