1) Don't use thirty pound backing with most trout fly lines, most fly lines are made with 20 pound test cores up thru 7 weight. With the eight weights and up they go to 30 pound test cores. With thirty pound backing it is much easier to break off your fly line if you should have a failure.

2) I base my tippet choice on three factors. a) water clarity-with an of color I go bigger, for low and clear conditions I go smaller. b) hook size, a small thin wire hook will straighten out with a heavy tippet, likewise a thicker diameter larger hook is harder to set with the stretch inherent in lighter tippets c) the size and fighting ability of the fish. Obviously you want to go with as heavy a tippet as you can get away with considering the other factors.

Fluorocarbon is not necessary for all applications. While I use it for all my steelhead and salmon fishing. I rarely use it for bass, and for most trout fishing I find the correct diameter and it's effects on natural drifts is more important then visibility.

3) I dont find to much effect of fly line color for most trout fishing. I tend to prefer lighter colors because the blend in better with the sky, fish are looking up and can see dark colors easier. I do find that the "flash" of a line can have a lot of effect on flats fish in shallow water. For Carp on the Great Lakes I use the "little Tunny" clear camo intermediate. A lot of flats fisherman in the Keys have found clear Crystal line to be very effective.