The only "diffrent" color floating fly line I have noticed is the clear creek series its an olive color very nice line, I used it on a 5wt for several years, Cortland makes it. If you do find a blue line it will more then likly be for salt water, so it would suck for cold water/weather fishing.
On the backing, 30 lb is over kill for trout, 20 is fine, gelspun backing is pretty good. I have caught some big trout in the 15-20 lb range and only had a few get into my backing a little.
Tippet ?, one thing you need to keep in mind is that floro. sinks, so if you are going to fish dries get some mono as well. The Smaller the fly the smaller the tippet, the bigger the fly the bigger the tippet, so get a few diffrenet sizes, from 7x to 3x. I usally carry 7X,5x,4X and 3x
Hope this helps