Contrary to popular belief, fluorocarbon isn't invisible underwater. I think it's less visible than monofilament and provides good strength. Depends a lot on brand though. I wouldn't buy a brand like Berkley Vanish.
boss's daughter? waitress who was serving? the guy who drives the forklift down in the warehouse?
Actually a couple guys in a truck. They were aggressive, but I think they were good people.
With the low diameter lines like Trilene XL(not XT) just buy 2lb tests higher than you normally would. With a good knot it should hold up just as well. I actually think of them as superior to other mono because of the smooth handling. But remember, strong knots...