Flouro is a good idea on some of the more pressured tailwaters. The Frying Pan and the Taylor for example. It could be the difference between a skunking and a 20+ fish day. Honestly, I think it's a good idea in pretty much any tailwater. On free stones the trout are not as wary and there's really no need to fish Flouro.
As far as tippet size goes, I rarely fish anything thicker than 5x, unless I'm stripping streamers then I'll go down to 3x or 4x. On highly pressured tailwaters you won't be catching much on anything stronger than 5x, again unless you're fishing streamers. Sometimes, especially in lower flows, 5x won't cut it. I downgrade to 6x or 7x in that case. I've yet to come across a situation where I actually needed to fish 8x, I don't think it's ever necessary.
On regular freestones, tippet size is also not as important. I fish 5x pretty much always on a freestone. Hope this helps.