There are two series of products available for IoT now.
Please refer page 7 for WICED Wi-Fi, and page 8 and 9 for WICED Smart of following document.
For WICED Smart, below link also helps your understanding.
WICED Sense is a kind of reference design with full source code, schematic and so on.
Do we need development boards or evaluation boards to program the Wiceds or we can simply program via USB ?
Programming your application to WICED module doesn't need the EVB. But recommended to use it during development of your application.
It would be nice if you please tell me the limitations , if we are not using any EVBs?
And do i need any other hardwares to develop some applications?
In short, what I need to develop applications with WICED?
If you have less than 5 years of low level embedded development experience, I'd recommend the Anaren Atmosphere environment for WICED Smart, which is based on Broadcom's Bluetooth Low Energy offering.
Their development environment is very easy to use and their support is excellent.