Coil Wire: If you mean the wire from the coil to the spark plug, yes it unscrews.
Rebuild Water Pump: You can replace the two outer seals without removing the cover, but it is hard…tight. If you need to replace the drive gear and bearing, you must drain the oil and remove the cover. It’s easier to replace all the parts with the cover removed. Go to Honda Parts Direct.com and print the Water Pump drawing. You may need to replace gaskets, too.