Change it every 5 years or 60,000 miles whichever come first.
Every 50,000 miles or 5 years. Read your owners manual maintenance schedule.
Change it every 100,000 miles on the 4 cylinder and change it at 105,000 miles on the V6 at the same time you have the cam belt and water pump replaced.
Every time you change the coolant.
15000 miles
Good question. I'm trying to find the answer myself. Closest I find is in the owner's manual on page 199, where it says "Replace engine coolant" without any mileage or time numbers.
Honda recommends @ 45k miles and then every 30k miles after that.
I recommend every 75,000 miles.
Honda recommends changing it at 100,000 miles. I personally recommend you change it every 75,000 miles. The 2003 Honda Accord had problems with the transmission so I would recommend this as a preventative measure.
Every 110,000 miles on the V6 and never on the 4 cylinder.
I don't know about 2006, in the 2001 it's at 105k miles
Change it every time you change your oil, 3 months or 3000 miles. Every 40,000km. More often under dusty conditions.