What are the deployment needs which are more popular IOC containers (example: Windsor, Ninject, Oneness, StructureMap, Autofac) ? Will they all deploy exactly the same?

If you are on the shared host, what challenges will that present (ex. medium trust, etc...)

Do they really be bin used? GAC used?

Any web-hosters which come "IOC-ready"?

The majority of the IOC frameworks works together with private devices and that i have no idea much Web hosters that enables you to definitely deploy files in to the GAC.