It really depends on where you live. If you live in an extremely cold climate, then run 70 antifreeze/30water, or really hot = 30 antifreeze/70water.
The reason the coolant appears to be orange is because the radiator and the block have some rust. This is normal. Iron + Oxygen = rust. But you should flush the system like stated above. That should remove the rust.
If you are really lazy (or don't want to unplug the radiator hoses and make a mess in your garage/street), you could unscrew the drain plug on the radiator, let it drain, put the plug back in & fill it back up with water only. Drive it till the engine is hot, drain, then refill w/ water. Repeat the process until the water drains perfectly clear. Then add your custom mix of antifreeze/water and you are set.
Autozone sells some radiator flush stuff too. Just depends on how you want to tackle the operation.
Scott