re: safe to swim FC level. If you're not algae, it generally won't hurt you to swim in a pool with a high(er) FC level. It may dry your skin a bit more and may/will be tougher on swimsuits (especially the elastic parts), but it generally won't hurt you.

re: bleaching out of test results. Yup, that happens. What I usually do is to add a drop or two of chlorine-neutralizer (dilute sodium thio-sulfate?) to the test vial and swirl and then proceed to check TA and CH. I have rarely seen pH test bleach-out problems. Some test kits are more sensitive than others to reagent bleach out. Speaking of which, I need to get some more thio. <grin>

re: CYA and high chlorine. AFAIK, the CYA test will not really suffer from any bleach out problem with high FC levels. The test uses a different type of indicator than a color-change, it uses a precipitation reaction with the CYA (which makes the milky/cloudy mix that you then try to read when the black dot disappears).

As to where your CYA went, the algae most likely ate it. Really.