Greetings From Arench!
To generalize struts last about 60-80k miles under most conditions. Driving over rough roads like potholes or dirt roads can shorten strut life. Driving a car thats often heavily loaded down can also shorten strut life. Operating the car in extreme temperatures either hot or cold will shorten strut life.
If a car drives on perfect roads in a mild climate with only one or two passengers the struts may last 100k miles or more.
When struts are going bad the symptoms will be excessive bounce when hitting a bump, bottoming out going over large bumps like a speed bump, rattling noise while driving over small road imperfections, or visible oil leaking from strut.
The V-6 camrys are heavier in the front from the big 3.5 engine so they are more sensitive to front struts wearing out than the lighter 4-cylinder models.
Front struts with alignment on this car is about 650 dollars plus taxes (if applicable)
Rear struts generally last longer than front because there is less weight for them to manage in the rear.
You can bounce test the car by pushing down has hard as you can in each corner several times, when you let off the car should not continue to bounce, it should stop at is normal height.
When rear struts are worn more often than not it will cut a choppy pattern into the rear tires. Run your hand over the rear tires and see if the road surface of the tire is lumpy.
The picture below is a severe example of uneven tire wear due to a bad rear strut.