4 years, you are fine!

I do think there is better "braids" out there than the fireline. But I do believe the best of the best for throwing crappie jigs would be berkley nanofil.

As for the white line, just hit the last 2 feet with a sharpie of your choice to camo it up a bit. as long as the water is not clear you should be fine. If it is clear, you need to add a fluorocarbon leader to it.