They require very little maintenance, which is one of the reasons that they are so great. You may need to touch up the paint from time to time, and oil the door hinges, but for the most part they are very, very low maintenance.
Used shipping containers are usually about 10 years old, but with a new paint job they can usually like like they are in like new condition. While 10 years old may seem like a long time, containers can last up to 50 years or more.
WWT stands for wind and water tight which means they are a good option for storing things safely. CWO means cargo worthy which means that the containers are certified to be able to be stacked seven high on a container ship.
40' of space is needed for a tilt bed truck, and 60' of space for roll off trucks. You will need 10' of width to fit the truck and 13'6" of height clearance and up to 16' where the container will be tilted off the truck.